The Collaborative International Dictionary of English v.0.48:

Palmaceae \Palmaceae\ n.
   A natural family of chiefly tropical trees and shrubs and
   vines usually having a tall columnar trunk bearing a crown of
   very large leaves; coextensive with the order Palmales.

   Syn: Palmae, family Palmae, family Palmaceae, Arecaceae,
        family Arecaceae, palm family.
        [WordNet 1.5]

WordNet (r) 3.0 (2006):

Palmaceae
    n 1: chiefly tropical trees and shrubs and vines usually having
         a tall columnar trunk bearing a crown of very large leaves;
         coextensive with the order Palmales [syn: Palmae, family
         Palmae, Palmaceae, family Palmaceae, Arecaceae,
         family Arecaceae, palm family]