Source : Webster's Revised Unabridged Dictionary (1913)

Calla \Cal"la\, n. [Linn[ae]us derived Calla fr. Gr. ??????? a
   cock's wattes but cf. L. calla, calsa, name of an unknown
   plant, and Gr. ????? beautiful.] (Bot.)
   A genus of plants, of the order {Arace[ae]}.

   Note: The common {Calla} of cultivation is {Richardia
         Africana}, belonging to another genus of the same
         order. Its large spathe is pure white, surrounding a
         fleshy spike, which is covered with minute apetalous
         flowers.

Source : WordNet®

calla
     n 1: South African plant widely cultivated for its showy pure
          white spathe and yellow spadix [syn: {calla lily}, {arum
          lily}, {Zantedeschia aethiopica}]
     2: water arum [syn: {genus Calla}]