'fit-looking' is a modern compound made in English by combining the adjective 'fit' (meaning physically in good condition) and the present-participle form 'looking' (from the verb 'look', meaning 'to have a certain appearance').

'fit' as an adjective (meaning healthy or physically sound) developed in Middle English from older Germanic roots, while 'look' comes from Old English 'lōcian' meaning 'to use the eyes, seem'. The two words have long been used together in phrases such as 'fit looking' and later often hyphenated to 'fit-looking' in modern usage.

Each element kept its basic sense: 'fit' meant physically able/healthy and 'looking' meant appearing; combined they came to specifically mean 'appearing physically healthy or attractive.'