Big and strongly muscled, in a heavy, solid way. It describes bodies and body parts — a brawny man, brawny arms, brawny shoulders — and it suggests strength built by physical work rather than in a gym; the picture behind it is a farmhand or a blacksmith, not a bodybuilder. It is a slightly old-fashioned, story-book word, common in novels and descriptions and rare in conversation, where people just say 'big' or 'well-built' or 'buff'. It is usually complimentary about strength, but it is not a compliment about looks — it says nothing about being handsome, and used of a woman it would sound unkind, so it is nearly always used of men. The noun behind it, 'brawn', means muscular strength, and you will most often meet it in the fixed contrast 'brains and brawn' — thinking versus physical power. Confusingly, 'brawn' in British English is also a cold meat made from a pig's head, but 'brawny' never means anything to do with that.