Implausibly

from WordNet (r) 3.0 (2006)

implausibly
    adv 1: not easy to believe; "behind you the coastal hills plunge
           to the incredibly blue sea backed by the Turkish
           mountains" [syn: {incredibly}, {improbably},
           {implausibly}, {unbelievably}] [ant: {believably},
           {credibly}, {plausibly}, {probably}]

from The Collaborative International Dictionary of English v.0.48

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.
   [1913 Webster]

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