The term 'BRAIN's Counterpart' can be solved by the five-letter word 'BRAWN'. BRAWN is a term used to describe physical strength or power, and is often seen as the opposite of brainpower. It is typically used to refer to the strength of an individual, rather than the collective strength of a group. In this context, it can be seen as the counterpart to the BRAIN, which is responsible for intellectual and cognitive abilities.