1. any of numerous perennial bulbous herbs having linear or broadly lanceolate leaves and usually a single showy flower;
The Collaborative International Dictionary of English v.0.48:
Tulip \Tu"lip\ (t[=u]"l[i^]p), n. [F. tulipe, OF. also tulipan,
It. tulipano, tulipa, from Turk. tulbend, dulbend, literally,
a turban, Per. dulband; -- so called from the resemblance of
the form of this flower to a turban. See Turban.] (Bot.)
Any plant of the liliaceous genus Tulipa. Many varieties
are cultivated for their beautiful, often variegated flowers.
(a) A large American tree (Liriodendron tulipifera) of the
magnolia family (Magnoliaceae) bearing tuliplike
flowers. See Liriodendron.
(b) A West Indian malvaceous tree (Paritium tiliaceum syn.
[1913 Webster + PJC]
WordNet (r) 3.0 (2006):
n 1: any of numerous perennial bulbous herbs having linear or
broadly lanceolate leaves and usually a single showy flower