Source : Webster's Revised Unabridged Dictionary (1913)

Impasse \Im`passe"\ ([a^]N`p[aum]s"; E. [i^]m*p[.a]s"), n. [F.]
   An impassable road or way; a blind alley; cul-de-sac; fig., a
   position or predicament affording no escape.

         The issue from the present impasse will, in all
         probability, proceed from below, not from above.
                                                  --Arnold
                                                  White.

Source : WordNet®

impasse
     n 1: a situation in which no progress can be made or no
          advancement is possible; "reached an impasse on the
          negotiations" [syn: {deadlock}, {dead end}, {stalemate},
           {standstill}]
     2: a street with only one way in or out [syn: {blind alley}, {cul
        de sac}, {dead-end street}]