Source : Webster's Revised Unabridged Dictionary (1913)

Mericarp \Mer"i*carp\, n. [Gr. ? a part + ? fruit.] (Bot.)
   One carpel of an umbelliferous fruit. See {Cremocarp}.

Source : WordNet®

mericarp
     n : a carpel with one seed; one of a pair split apart at
         maturity