: the same as something previously mentioned
used chiefly in bibliographies

Word History


Middle English, from Latin, same — more at identity

First Known Use

before the 12th century, in the meaning defined above

Time Traveler
The first known use of idem was before the 12th century

Dictionary Entries Near idem

Cite this Entry

“Idem.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/idem. Accessed 28 Sep. 2023.

Legal Definition


: something previously mentioned : the same authority
used in citations to cases and other works to refer to an immediately preceding reference
compare infra, supra

Note: Idem is usually used in the form of its abbreviation id.


Latin, same

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