From The Collaborative International Dictionary of English v.0.48 [gcide]:
philadelphus \philadelphus\ n.
Any of various chiefly deciduous ornamental shrubs of the
genus Philadelphus having white sweet-scented flowers,
single or in clusters; it is widely grown in temperate
regions.
[WordNet 1.5]
From WordNet (r) 3.0 (2006) [wn]:
philadelphus
n 1: any of various chiefly deciduous ornamental shrubs of the
genus Philadelphus having white sweet-scented flowers,
single or in clusters; widely grown in temperate regions