Source : Webster's Revised Unabridged Dictionary (1913)

Caducous \Ca*du"cous\, [L. caducus falling, inclined to fall,
   fr. cadere to fall. See {Cadence}.] (Bot. & Zo["o]l.)
   Dropping off or disappearing early, as the calyx of a poppy,
   or the gills of a tadpole.

Source : WordNet®

caducous
     adj : shed at an early stage of development; "most amphibians have
           caducous gills"; "the caducous calyx of a poppy" [syn:
           {shed}] [ant: {persistent}]