Source : Webster's Revised Unabridged Dictionary (1913)

Oncidium \On*cid"i*um\, n. [NL.] (Bot.)
   A genus of tropical orchidaceous plants, the flower of one
   species of which ({O. Papilio}) resembles a butterfly.

Source : WordNet®

oncidium
     n : any orchid of the genus Oncidium: characterized by slender
         branching sprays of small yellow and brown flowers; often
         grown as houseplants [syn: {dancing lady orchid}, {butterfly
         plant}, {butterfly orchid}]