c. 1300, "an ox, bull, or cow," also the flesh of one when killed, used as food, from Old French buef "ox; beef; ox hide" (11c., Modern French boeuf), from Latin bovem (nominative bos, genitive bovis) "ox, cow," from PIE root *gwou- "ox, bull, cow." The original plural in the animal sense was beeves.
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).
<a href="https://www.etymonline.com/word/beefy">Etymology of beefy by etymonline</a>
Harper, D. (n.d.). Etymology of beefy. Online Etymology Dictionary. Retrieved $(datetime), from https://www.etymonline.com/word/beefy