In 1906 the University of Chicago Press's first Manual of Style printed a model run of footnotes: "Spencer, Principles of Sociology, chap. 4.", then "Ibid.", then "Ibid., chap. 5.", then "Spencer, loc. cit." (University of Chicago Press, 1906, rule 215). In March 2026 the fifth edition of OSCOLA, the UK law schools' footnote style, told writers to stop using ibid. (Goudkamp, 2026).
EdCitation publishes this guide: each abbreviation's meaning from a dictionary, where they came from, and what each style's publisher says now, all read on 26 September 2026. Where a rule sits behind a subscription, we say so.
Each abbreviation leans on a full reference. EdCitation's Cite a source builds it from the publisher's record in APA 7, MLA 9, Chicago 18 author-date, Harvard, IEEE and Vancouver. It writes no footnotes: its Chicago is author-date, where notes do not apply.
What do ibid., op. cit. and loc. cit. mean?
Each is a Latin phrase pointing back to a source already cited. Ibid. is short for ibidem, "in the same place"; op. cit. for opere citato, "in the work cited"; loc. cit. for loco citato, "in the place cited" (Dictionary.com, n.d.-c, n.d.-f, n.d.-e).
| Abbreviation | Latin | Meaning | What it does in a note |
|---|---|---|---|
| ibid. | ibidem | in the same place | Repeats the source of the note just before |
| id. or idem | idem | the same | Repeats the author just named |
| op. cit. | opere citato | in the work cited | Points to an earlier note by the same author, with a new page |
| loc. cit. | loco citato | in the place cited | Points to the same page of that earlier note |
| et al. | et alii | and others | Shortens a list of authors |
| cf. | confer | compare | Sends the reader to a source to set beside this one |
| passim | passim | here and there | Says a point runs through a whole work or range of pages |
Meanings from Dictionary.com (n.d.-a, n.d.-b, n.d.-d, n.d.-g).
The three in a run of notes
Say note 1 cites Grafton's book in full. Note 2, "Ibid., 45", means the same book, page 45. Note 3 cites someone else. Note 4, "Grafton, op. cit., 60", means the Grafton work cited earlier, page 60; "Grafton, loc. cit." means the very page given before. Each sends the reader searching backwards, the complaint every modern style makes.
Where did the Latin abbreviations come from?
From the footnote, written for readers expected to know Latin; its history, from medieval glosses to Gibbon and Ranke, is in who invented the footnote. When ibid. first appeared in English print we could not confirm, as the OED needs a subscription. Dictionary.com (n.d.-d) dates idem in English to between 1350 and 1400.
What the 1906 Chicago manual asked for
It italicised ibid., idem, loc. cit., op. cit., supra, infra and passim, but not cf., i.e. or e.g. (University of Chicago Press, 1906, rule 53). Rule 215 prescribed ibid. for closely consecutive references, except in the first note on a left-hand page, where the title, loc. cit. or op. cit. was better. Chicago now sets ibid. in roman type (University of Chicago Press, n.d.-c).
How they faded
Pollak (2006), surveying a century of the Chicago manual, says in the article's abstract that loc. cit. and op. cit. gave way to "almost plain English", while ibid. survived. Then Chicago's 17th edition began to discourage ibid. (University of Chicago Press, 2017). The MLA said in 2016 that "the days of expecting an educated person to know Latin and Greek are over" (Modern Language Association, 2016). More retired rules: retired citation rules you can stop following.
Which citation styles still allow ibid. today?
Only footnote styles, and fewer each edition: Chicago's notes permit it, MHRA allows it sparingly, and OSCOLA dropped it in 2026. Author-date and numbered styles never needed it.
| Style | ibid. | op. cit. and loc. cit. | Write instead | Built by EdCitation |
|---|---|---|---|---|
| Chicago 18, notes | Allowed, discouraged | Sections not read | Author and short title, or author alone | No |
| Chicago 18, author-date | Discouraged | Not applicable | (Pollak 2006, 22) again | Yes, in Cite a source |
| MLA 9 | Not used | Not used | Author and page, or page alone when clear | Yes, MLA 9 |
| APA 7 | Not used | Not used | Author and year every time in brackets | Yes |
| Harvard (Cite Them Right) | Not used | Not used | Author and year again | Yes |
| IEEE | Removed | Removed | The earlier number: [3, pp. 5–10] | Yes |
| Vancouver | Not mentioned | Not mentioned | The source's first number again | Yes |
| OSCOLA 5 | Not used | Avoid | Stevens (n 1) 110 | No |
| MHRA 4 | Sparingly | Not used | Author, short title and page | No |
Chicago: discouraged since the 17th edition
Chicago said in 2017 that its 17th edition would discourage ibid. in favour of shortened citations, because it can confuse readers of electronic formats that link to one note at a time; it did not ban it (University of Chicago Press, 2017). Its example uses the author alone: "1. Morrison, Beloved, 3." then "2. Morrison, 18."
The 18th edition (2024) holds that line. Chapter 13 has sections headed "Shortened citations versus 'ibid.'" (13.37), "Idem" (13.38) and "Op. cit. and loc. cit." (13.39) (University of Chicago Press, n.d.-a). Asked whether ibid. is gone, Chicago's editors said no: a short citation is preferred, but writers free to choose may use it (University of Chicago Press, n.d.-d). The text of 13.38 and 13.39 is behind the subscription, so we could not confirm what it says. Chicago's free notes samples use only shortened notes, such as "Yu, Interior Chinatown, 48" (University of Chicago Press, n.d.-e).
In author-date, the Chicago EdCitation builds, a parenthetical citation is already a short form, so Chicago discourages ibid. there too (University of Chicago Press, n.d.-b): write (Pollak 2006, 22) again. See the Chicago author-date referencing guide and the history of the Chicago Manual of Style.
MLA and APA: not at all
The MLA avoids ibid. and op. cit. and uses short titles, so nobody must look back (Modern Language Association, 2016). That answer dates from the eighth edition; in the ninth, a page number stands alone when the author is named in the sentence: "(194)" (Modern Language Association, 2021).
APA shows a repeated citation in full, because ibid. "is not used in APA Style"; only a narrative citation may drop the year after its first mention in a paragraph (American Psychological Association, 2019). APA keeps cf., e.g., i.e. and viz. inside parentheses, never italicises them, and uses et al. in both narrative and parenthetical citations (American Psychological Association, 2022).
Harvard: Cite Them Right says no, one university shrugs
Cite Them Right, which Birmingham City University calls widely adopted in British universities, says ibid. and op. cit. are not used in Harvard, where each work appears once in an alphabetical list. Its subscription site could not be read; the wording is Birmingham City University's quotation of the 12th edition (Birmingham City University, n.d.). That page also disagrees: Harvard has no manual, so nothing forbids them. For Cite Them Right Harvard, which EdCitation builds, the answer is no. That quotation spells the Latin "opera citato"; the dictionary has opere citato (Dictionary.com, n.d.-f).
IEEE and Vancouver: the number does the work
A source keeps its number, so there is nothing to abbreviate. IEEE's Reference Guide says to remove ibid. and op. cit., cite the earlier number, and put new detail in the brackets: [3, pp. 5–10] (IEEE, 2025). For Vancouver, the ICMJE numbers references in order of first mention (International Committee of Medical Journal Editors, n.d.) and does not mention ibid. More in the IEEE and Vancouver guides.
What changed for OSCOLA and MHRA?
Both UK footnote styles have turned against the Latin. EdCitation does not build either yet.
OSCOLA's fifth edition drops ibid.
The fourth edition, of 2012, let ibid. repeat the citation in the footnote just before, while listing supra, infra, id., op. cit. and loc. cit. as "Latin gadgets" to avoid (Meredith & Nolan, 2012). The fifth, published on 25 March 2026, adds ibid. to the gadgets: a later citation names the source briefly and points to the footnote with the full one, as in "Stevens (n 1) 110" (Goudkamp, 2026). Oxford's list of key changes records it (University of Oxford Faculty of Law, 2026). Eg, ie and cf remain; the fourth edition noted that cf means "compare", not "see". Background: law books and textbooks for students.
MHRA: ibid. sparingly, op. cit. never
The MHRA Style Guide's fourth edition calls loc. cit. and op. cit. too vague to use, and allows ibid. only where nothing can be confused, such as a repeat no more than four lines of typescript after the reference before it (Modern Humanities Research Association, 2024, §7.12). It rules out id., and in a full reference asks for "and others", not et al.
What about idem, cf., passim and et al.?
Idem (id.) repeats an author, not a work; MHRA and OSCOLA reject it, and Chicago's section on it we could not read. Cf. survives in APA's parentheses and OSCOLA's notes. Passim lives on in indexes, as in "coal: 78–86 passim" (Dictionary.com, n.d.-g); no current style page we read gives it a place in citations. Et al. is the one most styles keep, each with its own author count, though MHRA prefers "and others": see when to use et al..
How do I replace ibid. and op. cit. in my paper?
Swap each for your style's short form, built on a correct full reference.
- Find the style. EdCitation's free Check your paper reads the brief into a checklist that includes the style.
- Build each full reference in Cite a source, from a DOI, ISBN, PubMed ID, title or web address.
- Author-date styles: repeat author and year with the page: (Pollak, 2006, p. 22) in APA, (Pollak 2006, 22) in Chicago.
- MLA 9: author and page, or the page alone when the author is named in your sentence.
- IEEE and Vancouver: reuse the first number, with a page in IEEE's brackets where needed.
- Footnote styles: replace ibid. with author and short title, per Chicago's samples, MHRA, or OSCOLA's "Stevens (n 1) 110".
- Clear the list of any ibid. or op. cit. line, then paste it into Verify references.
Which EdCitation tools help with repeated citations?
Cite a source is the best tool for the step every short form rests on: EdCitation looks the reference up in the publisher's record and never writes one, which no chatbot can do. It is free with no account, builds the six styles above and screens each source for retraction.
A book by ISBN and an article by DOI
Quoted exactly from runs on 26 September 2026. From ISBN 9780674307605, Grafton's history of the footnote, Chicago 18 author-date gave:
Grafton, Anthony. 1999. The Footnote: A Curious History. Harvard University Press.
and MLA 9:
Grafton, Anthony. The Footnote: A Curious History. Harvard UP, 1999.
Its publisher dates that paperback April 1999. From Pollak's DOI, 10.3138/jsp.38.1.14, Chicago 18 author-date gave:
Pollak, Oliver B. 2006. “The Decline and Fall of Bottom Notes, Op. Cit., Loc. Cit., and a Century of the Chicago Manual of Style.” Journal of Scholarly Publishing 38 (1): 14–30. https://doi.org/10.3138/jsp.38.1.14.
and MLA 9:
Pollak, Oliver B. “The Decline and Fall of Bottom Notes, Op. Cit., Loc. Cit., and a Century of the Chicago Manual of Style.” Journal of Scholarly Publishing, vol. 38, no. 1, Oct. 2006, pp. 14–30, https://doi.org/10.3138/jsp.38.1.14.
The Latin is italic as in the publisher's record. In-text forms were "(Pollak 2006)" and "(Pollak)"; add the page.
Verify references on a short list
EdCitation's Verify references, free with no account, took three Chicago author-date entries: Pollak's, Grafton's 1994 History and Theory article dated 1998, and one we invented, "Ibid. and the Vanishing Footnote in Digital Scholarship". Pollak's came back verified: "The DOI resolves to this record and the title matches." Grafton's came back "check this": "A record with this title exists, but it was published in 1994, not 1998." The invented one came back not found: "No publisher's or registry's record matches this reference."
A second list carried "Ibid., 22." and "Pollak, op. cit., 25." as lines of their own: the ibid. line was left out of the results, and the op. cit. line came back not found. An entry that cannot be checked is labelled "could not check", never "not found". For a whole paper, References from a file, part of Pro at $8 a month, checks every reference and matches each in-text citation to the list.
Quick questions
What does ibid. mean in a citation?
Ibid. is short for the Latin ibidem, "in the same place". In a footnote it repeats the source of the note just before.
Can I use ibid. in APA or Harvard referencing?
No. APA Style does not use ibid. and repeats the author and year each time; Cite Them Right Harvard uses neither ibid. nor op. cit.
Does Chicago's 18th edition still allow ibid.?
In notes, yes, but it is discouraged in favour of a shortened citation. In Chicago author-date, repeat author, year and page instead.
Did OSCOLA drop ibid.?
Yes. OSCOLA's fifth edition (March 2026) uses a short form and a cross-citation instead: "Stevens (n 1) 110".
Can EdCitation write ibid. or footnotes for me?
No. EdCitation's Cite a source builds the full reference and in-text citation in six styles, Chicago as author-date; notes are written from your style's guide.
References
- American Psychological Association. (2019). Author–date citation system. APA Style. https://apastyle.apa.org/style-grammar-guidelines/citations/basic-principles/author-date
- American Psychological Association. (2022). APA Style abbreviations guide [PDF]. https://apastyle.apa.org/instructional-aids/abbreviations-guide.pdf
- Birmingham City University. (n.d.). Harvard referencing: Common questions. Library and Learning Resources. Retrieved 26 September 2026, from https://www.bcu.ac.uk/library/services-and-support/referencing/harvard/common-questions
- Dictionary.com. (n.d.-a). Cf. In Dictionary.com Unabridged. https://www.dictionary.com/browse/cf
- Dictionary.com. (n.d.-b). Et al. In Dictionary.com Unabridged. https://www.dictionary.com/browse/et-al
- Dictionary.com. (n.d.-c). Ibid. In Dictionary.com Unabridged. https://www.dictionary.com/browse/ibid
- Dictionary.com. (n.d.-d). Idem. In Dictionary.com Unabridged. https://www.dictionary.com/browse/idem
- Dictionary.com. (n.d.-e). Loco citato. In Dictionary.com Unabridged. https://www.dictionary.com/browse/loco-citato
- Dictionary.com. (n.d.-f). Op. cit. In Dictionary.com Unabridged. https://www.dictionary.com/browse/op-cit
- Dictionary.com. (n.d.-g). Passim. In Dictionary.com Unabridged. https://www.dictionary.com/browse/passim
- Goudkamp, J. (Ed.). (2026). OSCOLA: The Oxford University standard for citation of legal authorities (5th ed.) [PDF]. Faculty of Law, University of Oxford. https://www.law.ox.ac.uk/sites/default/files/2026-03/OSCOLA%205.pdf
- IEEE. (2025). IEEE reference guide (V 3.28.2025). IEEE Author Center. https://journals.ieeeauthorcenter.ieee.org/wp-content/uploads/sites/7/IEEE_Reference_Guide.pdf
- International Committee of Medical Journal Editors. (n.d.). Preparing a manuscript for submission to a medical journal. ICMJE Recommendations. https://www.icmje.org/recommendations/browse/manuscript-preparation/preparing-for-submission.html
- Meredith, S., & Nolan, D. (Eds.). (2012). OSCOLA: Oxford University standard for the citation of legal authorities (4th ed.) [PDF]. Faculty of Law, University of Oxford. https://www.law.ox.ac.uk/sites/default/files/2026-04/OSCOLA_4_IntLaw2006.pdf
- Modern Humanities Research Association. (2024). MHRA style guide: A handbook for authors and editors (4th ed., chap. 7). https://www.mhra.org.uk/style/chapter7.html
- Modern Language Association. (2016, October 13). Is using ibid. allowed for in-text citations? If so, how is it done? MLA Style Center. https://style.mla.org/ibid/
- Modern Language Association. (2021, April 1). In-text citations: An overview. MLA Style Center. https://style.mla.org/in-text-citations-overview/
- Pollak, O. B. (2006). The decline and fall of bottom notes, op. cit., loc. cit., and a century of the Chicago Manual of Style. Journal of Scholarly Publishing, 38(1), 14–30. https://doi.org/10.3138/jsp.38.1.14
- University of Chicago Press. (n.d.-a). Chapter 13: Source citations: Overview [Contents]. The Chicago Manual of Style (18th ed.). https://www.chicagomanualofstyle.org/book/ed18/part3/ch13/toc.html
- University of Chicago Press. (n.d.-b). Citation, documentation of sources (Q&A No. 10). The Chicago Manual of Style Online. https://www.chicagomanualofstyle.org/qanda/data/faq/topics/Documentation/faq0010.html
- University of Chicago Press. (n.d.-c). Citation, documentation of sources (Q&A No. 93). The Chicago Manual of Style Online. https://www.chicagomanualofstyle.org/qanda/data/faq/topics/Documentation/faq0093.html
- University of Chicago Press. (n.d.-d). Citation, documentation of sources (Q&A No. 329). The Chicago Manual of Style Online. https://www.chicagomanualofstyle.org/qanda/data/faq/topics/Documentation/faq0329.html
- University of Chicago Press. (n.d.-e). Notes and bibliography: Sample citations. The Chicago Manual of Style Online. https://www.chicagomanualofstyle.org/tools_citationguide/citation-guide-1.html
- University of Chicago Press. (1906). Manual of style: Being a compilation of the typographical rules in force at the University of Chicago Press, to which are appended specimens of types in use. https://archive.org/details/manualofstylebei00univrich
- University of Chicago Press. (2017, May 4). What's new in the CMOS 17 citation chapters. CMOS Shop Talk. https://cmosshoptalk.com/2017/05/04/whats-new-in-the-cmos-17-citation-chapters/
- University of Oxford Faculty of Law. (2026). Key changes made in the fifth edition of OSCOLA [PDF]. https://www.law.ox.ac.uk/sites/default/files/2026-04/OSCOLA%20key%20changes.pdf