The quality of being muscular and physically strong.
From 'brawny' (muscular) + '-ness' (suffix forming nouns). Brawny comes from Old French 'braon' meaning meat or muscle, ultimately from Germanic roots relating to flesh.
Brawniness literally means you have a lot of 'brawn' — which originally just meant meat or muscle tissue on animals, but evolved to describe human physical strength and power.
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