Source : Webster's Revised Unabridged Dictionary (1913)

Immaturity \Im`ma*tu"ri*ty\, n. [L. immaturitas: cf. F.
   immaturit['e].]
   The state or quality of being immature or not fully
   developed; unripeness; incompleteness.

         When the world has outgrown its intellectual
         immaturity.                              --Caird.

Source : WordNet®

immaturity
     n : not having reached maturity [syn: {immatureness}] [ant: {maturity}]