What does alibi mean?
An alibi is a claim, supported by evidence or testimony, that a person was in a different place at the time a crime or other alleged act occurred — and therefore could not have committed it. The word comes directly from Latin, where alibi means "elsewhere," and entered English legal usage in the early seventeenth century. Its primary sense remains firmly tied to criminal law, where establishing a credible alibi can be decisive: witnesses, receipts, surveillance footage, or phone records may all serve to place someone elsewhere. Over time a second, figurative sense developed, now entirely standard, in which an alibi is any excuse offered to justify conduct or deflect criticism — as in "using tiredness as an alibi." This looser use often implies skepticism about the excuse's sincerity. Common collocations include "provide an alibi," "establish an alibi," and the emphatic "airtight" or "ironclad alibi." Related but distinct is the noun "alias," which refers to an assumed name rather than a claimed whereabouts. Versatile in both formal and informal registers, alibi is a useful word precisely because it bridges the courtroom and everyday conversation.
A claim or evidence that a person was in a different place when an act, especially a crime, is alleged to have taken place; by extension, an excuse offered to justify or explain one's behavior.
"Witnesses placed her at a restaurant across town, giving her an airtight alibi."
In legal usage the term is precise and evidentiary; in general speech the figurative sense often suggests doubt about the excuse being offered.
(Informal, chiefly North American) To provide an alibi for someone; to offer an excuse on behalf of oneself or another.
"He tried to alibi his absence by blaming the traffic."
This verbal use dates from the mid-twentieth century and remains informal; some style guides still regard it as casual.
The standard plural follows regular English -s inflection; the original Latin form is an indeclinable adverb, so no classical plural exists.
"Detectives interviewed three suspects whose alibis all contradicted one another."
"Alibi" is simply the Latin word for "elsewhere" — so every time someone offers one, they're literally pleading, in ancient Roman, "I was somewhere else."
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Etymology of alibi
Alibi comes straight from the Latin adverb alibi, meaning "elsewhere" or "in another place." English borrowed the term in the early seventeenth century as a legal term of art, using it in the phrase "the plea of alibi" — a defense asserting the accused was elsewhere when the offense occurred. It shares its origin with the Latin pronoun alius, "other" or "another," the same root that gives us words such as alias, alien, and alienate.
How alibi is actually used
The figurative sense ('an excuse for anything') was once criticized as a loose extension but is now fully standard in both British and American English. The plural is conventionally 'alibis'. In legal contexts the word carries precise evidentiary weight; in everyday speech it often carries a whiff of suspicion, implying the speaker doubts the excuse.
Easily confused with alibi
An alibi is evidence that one was somewhere else at a given time, whereas an alias is a false or alternative name a person goes by.