'male-only' is a compound of the words 'male' and 'only'; 'male' originates from Old French, specifically the word 'masle', where the root 'mas-' came ultimately from Latin 'masculus' meaning 'male'; 'only' originates from Old English, specifically the word 'ānlic', where 'ān' meant 'one'.

'male-only' developed as a descriptive phrase in Modern English from earlier separate words such as Middle English forms of 'male' and 'only' (for example, 'male onlie'), and over time the hyphenated compound 'male-only' became common in contemporary usage.

Initially the elements referred simply to 'male' and 'one/sole'; over time the compound came to specifically mean 'restricted to males' in modern usage.