XanthoxylumXan*thox"y*lum\, n. [NL., from Gr. xanqo`s yellow + xy`lon wood.] (Bot.) A genus of prickly shrubs or small trees, the bark and rots of which are of a deep yellow color; prickly ash. Note: The commonest species in the Northern United States is Xanthoxylum Americanum. See Prickly ash, under Prickly.