The Oxford Thesaurus An A-Z Dictionary of Synonyms - plausible adj.

1) likely, believable, reasonable, credible, tenable, conceivable, thinkable, probable, imaginable, admissible, sound, sensible, rational, logical, acceptable, trustworthy, presentable: The police regarded our alibi as plausible. 2) specious, deceptive, meretricious, misleading, deceitful, casuistic, sophistical, Jesuitical, smooth, empty: He was a cunning, plausible sort of fellow.