Implausible

[ɪm'plɔːzɪb(ə)l] or [ɪm'plɔzəbl]

(adj.) having a quality that provokes disbelief; 'gave the teacher an implausible excuse' .

Edited by Claudette--From WordNet

(a.) Not plausible; not wearing the appearance of truth or credibility, and not likely to be believed.

Checker: Merle

adj. not plausible incredible.—n. Implausibil′ity.

Editor: Tamara