Source : Webster's Revised Unabridged Dictionary (1913)

Unambiguity \Un*am`bi*gu"i*ty\, n.
   Absence of ambiguity; clearness; perspicuity.

Source : WordNet®

unambiguity
     n : clarity achieved by the avoidance of ambiguity [syn: {unequivocalness}]
         [ant: {ambiguity}, {ambiguity}]