early 15c., "small piece of glittering metal," diminutive of spang "glittering ornament, spangle," probably from Middle Dutch spange "brooch, clasp," cognate with Old English spang "buckle, clasp," from Proto-Germanic *spango, from an extended form of PIE root *(s)pen- "to draw, stretch, spin."
-y 2
adjective suffix, "full of or characterized by," from Old English -ig, from Proto-Germanic *-iga- (source also of Dutch, Danish, German -ig, Gothic -egs), from PIE -(i)ko-, adjectival suffix, cognate with elements in Greek -ikos, Latin -icus (see -ic). Originally added to nouns in Old English; used from 13c. with verbs, and by 15c. even with other adjectives (for example crispy). Adjectives such as hugy, vasty are artificial words that exist for the sake of poetical metrics.