What is 'Ibid'?
'Ibid.' is short for the Latin ibidem, 'in the same place'. In a footnote or endnote, it points the reader back to the source cited in the note immediately before, so you do not have to repeat the full reference.
How to Use 'Ibid'
When two consecutive notes cite the same source, the second can read 'Ibid.' followed by the new page number, or 'Ibid.' alone when the page is the same.
Example:
1. John Smith, History of Modern Europe (Oxford: Example Press, 2021), 45.
2. Ibid., 52.
3. Ibid.
(An invented book.) Note 2 cites page 52 of the same book; note 3 cites page 52 again.
Usage Across Styles
- Chicago: the Chicago Manual of Style allows 'ibid.' but discourages it, and prefers a shortened citation (author's surname, short title, page) for a repeated source.
- OSCOLA (UK legal citation): uses 'ibid' for consecutive citations of the same source.
- APA, MLA and Harvard: these use in-text citations rather than notes, so 'ibid.' has no place in them.
Quick Answers
- Can you use ibid twice in a row? Yes. Each 'ibid.' refers to the note directly before it, so a run of notes to the same source can all use it.
- Ibid vs op. cit.: 'op. cit.' (opere citato, 'in the work cited') points to a source cited earlier but not in the previous note, together with the author's name. It is now outdated; use a shortened citation instead.
- Ibid vs id.: US legal citation (the Bluebook) uses 'id.' where other styles use 'ibid.'.
Best Practices
- Use 'ibid.' only when the previous note cites one source, and it is the same one.
- Add the page number when it changes; leave it out when it does not.
- If a different source comes in between, use a shortened citation instead.
- Re-check your notes after late edits: moving or deleting a note can leave an 'ibid.' pointing at the wrong source. A reference manager that generates the notes for you updates them automatically.
Full guide: Chicago Style Footnotes: Format, Examples and Ibid (CMOS 18)