WordNet (r) 3.0 (2006):

water elm
    n 1: Eurasian elm closely resembling the American elm; thrives
         in a moist environment [syn: water elm, Ulmus laevis]
    2: large ornamental tree with graceful gradually spreading
       branches common in eastern North America [syn: American
       elm, white elm, water elm, rock elm, Ulmus
       americana]