Source : Webster's Revised Unabridged Dictionary (1913)

Poinsettia \Poin*set"ti*a\ (poin*s[e^]t"t[i^]*[.a]), n. [NL.
   Named after Joel R. Poinsett of South Carolina.] (Bot.)
   A Mexican shrub ({Euphorbia pulcherrima}) with very large and
   conspicuous vermilion bracts below the yellowish flowers.

Source : WordNet®

Euphorbia pulcherrima
     n : tropical American plant having poisonous milk and showy
         tapering usually scarlet petallike leaves surrounding
         small yellow flowers [syn: {poinsettia}, {Christmas star},
          {Christmas flower}, {lobster plant}, {Mexican flameleaf},
          {painted leaf}]