'bachelorly' originates from English, specifically formed from the noun 'bachelor' plus the adjectival/ adverbial suffix '-ly' (meaning 'in the manner of' or 'having the qualities of').

'bachelor' in turn comes from Old French 'bacheler' (12th c.), which came from Medieval Latin 'baccalarius'/'baccalaureus' (meaning a young man, novice or holder of a bachelor's degree); the English adjective 'bachelorly' developed by adding '-ly' to 'bachelor'.

Initially, 'bachelor' referred to a young man or an inexperienced knight and later to an unmarried man; 'bachelorly' evolved to mean 'having the qualities or state of a bachelor' in modern usage.