The Collaborative International Dictionary of English v.0.48:

Unheritable \Unheritable\
   See heritable.
   [break]
   [1913 Webster]
   [1913 Webster] Unnoble
   Unniggard
   Unnegotiable
   Unneedful
   Unnavigable
   Unnative
   Unnamable
   Unmysterious
   Unmusical
   Unmuscular
   Unmotherly
   Unmonkish
   Unmoist
   Unmodish
   Unmodifiable
   Unmitigable
   Unmiry
   Unmiraculous
   Unmingleable
   Unmindful
   Unmilitary
   Unmild
   Unmighty
   Unmetaphorical
   Unmerry
   Unmeritable
   Unmerciable
   Unmercenary
   Unmentionable
   Unmendable
   Unmelodious
   Unmeet
   Unmeek
   Unmatronlike
   Unmatchable
   Unmasculine
   Unmarvelous
   Unmarriageable
   Unmarriable
   Unmarketable
   Unmanly
   Unmanlike
   Unmanful
   Unmanageable
   Unmalleable
   Unmakable
   Unmaidenly
   Unlusty
   Unlustrous
   Unluminous
   Unlucent
   Unlovable
   Unlosable
   Unlordly
   Unlogical
   Unlineal
   Unlimber
   Unlightsome
   Unlibidinous
   Unlevel
   Unladylike
   Unlaborious
   Unknowable
   Unknotty
   Unknightly
   Unkingly
   Unjustifiable
   Unjoyous
   Unjoyful
   Unjealous
   Uninvestigable
   Uninventive
   Uninterpretable
   Uninteresting
   Unintentional
   Unintelligible
   Unintelligent
   Uninstructive
   Uninquisitive
   Uninjurious
   Uninhabitable
   Uningenuous
   Uningenious
   Uninfluential
   Uninflammable
   Unindustrious
   Unindulgent
   Unindifferent
   Unincreasable
   Unincidental
   Unimpugnable
   Unimprovable
   Unimpressionable
   Unimpressible
   Unimportant
   Unimplicit
   Unimmortal
   Unimaginative
   Unimaginable
   Unillusory
   Unidle
   Unideal
   Unhygienic
   Unhhurtful
   Unhurt
   Unhostile
   Unhopeful
   Unhonorable
   Unhigh