brawn (n.) Look up brawn at Dictionary.com
late 13c., from Old French braon "fleshy or muscular part, buttock," from Frankish *brado "ham, roast" or some other Germanic source, from Proto-Germanic *bred-on- (cognates: Old High German brato "tender meat," German Braten "roast," Old Norse brað "raw meat," Old English bræd "flesh"), from PIE *bhre- "burn, heat," from root *bhreue- "to boil, bubble, effervesce, burn" (see brew (v.)). The original sense is "piece of meat suitable for roasting." "The specific sense 'boar's flesh' is exclusively of English development, and characteristic of English habits" [OED].