Plausible means it sounds true. The story hangs together, the times match, nothing in it makes you stop and frown — which is a long way from proof that it happened.
That built-in doubt is the point of the word. Calling an alibi plausible is not calling it honest; you are saying you cannot knock it down yet. It goes with explanation, excuse, alibi and theory, and with the set phrase plausible deniability — an arrangement where a boss can truthfully say nobody told them. Used about a person it is a warning: a plausible salesman is smooth, believable and worth watching. The noun is plausibility, the opposite is implausible, and the adverb plausibly does the same quiet undermining.
1adjectiveplausibleBelievable; reasonable enough that it could be true.
“She gave a plausible explanation for the missing money.”
synonyms: believable, credible, convincing
2adjectiveskilledSkilled at sounding convincing, whether honest or not.
“He was a plausible witness until the phone records appeared.”
Latin plausibilis meant 'deserving applause', from plaudere, 'to applaud' — the verb that also gave English applause. An argument that was plausible was one worth clapping for. English kept the approval and moved it from the hands to the head: now it names an argument you nod at, and possibly should not believe.
Latin
plausibilis — deserving applause, praiseworthy, acceptable, pleasing
English, today
plausible
Built from
From Latin plausibilis (“deserving applause, praiseworthy, acceptable, pleasing”), from the participle stem of plaudere (“to applaud”).
Etymology from Wiktionary, CC BY-SA