Source : Webster's Revised Unabridged Dictionary (1913)

Implausible \Im*plau"si*ble\, a. [Pref. im- not + plausible: cf.
   F. implausible.]
   Not plausible; not wearing the appearance of truth or
   credibility, and not likely to be believed. ``Implausible
   harangues.'' --Swift. -- {Im*plau"si*ble*ness}, n. --
   {Im*plau"si*bly}, adv.

Source : WordNet®

implausibly
     adv : not easy to believe; "behind you the coastal hills plunge to
           the incredibly blue sea backed by the Turkish
           mountains" [syn: {incredibly}, {improbably}, {unbelievably}]
           [ant: {believably}, {credibly}]