blossom: [OE] Blossom probably comes ultimately from an Indo-European base *bhlōs-, which was also the source of Latin flōs, from which English gets flower. It seems reasonable to suppose, in view of the semantic connections, that this *bhlōs- was an extended form of *bhlō-, from which English gets blade, bloom, and the now archaic verb blow ‘come into flower’. => blade, bloom, blow, flower
c. 1200, from Old English blostm, blostma "blossom, flower, fruit," from Proto-Germanic *blo-s- (cognates: Middle Low German blosom, Dutch bloesem, German Blust), from PIE *bhlow-, extended form of *bhel- (3) "to thrive, bloom" (see folio). This is the native word, now largely superseded by bloom (n.1) and flower (n.).