unplausible

adjective

1. having an appearance of truth or reason; seemingly worthy of approval or acceptance; credible; believable: a plausible excuse; a plausible plot.
2. well-spoken and apparently, but often deceptively, worthy of confidence or trust: a plausible commentator.

adjective

1. apparently reasonable, valid, truthful, etca plausible excuse
2. apparently trustworthy or believablea plausible speaker

adj.1540s, “acceptable, agreeable,” from Latin plausibilis “deserving applause, acceptable,” from plaus-, past participle stem of plaudere “to applaud” (see plaudit). Meaning “having the appearance of truth” is recorded from 1560s. Related: Plausibly.