"prickly seed vessel of some plants," c. 1300, burre, from a Scandinavian source (compare Danish borre, Swedish hard-borre, Old Norse burst "bristle"), from PIE *bhars- (see bristle (n.)). It was transferred 1610s to "rough edge on metal," which might be the source of the sense "rough sound of the letter -r-" (see burr). Also the name given to various tools and appliances.
-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.