'bailey' originates from Old French, specifically the word 'baillie' or 'bailey' (Old French 'baille'), where the root meant 'enclosure' or 'fortified area'.

'bailey' changed from Old French 'baille'/'baillie' into Middle English forms such as 'baili' or 'bailey', and later became the modern English word 'bailey' (plural 'baileys'). The surname 'Bailey' also developed from Middle English usage meaning a bailiff or steward.

Initially it referred to an 'enclosed area' or an official related to administration; over time it came to be used specifically for the courtyard of a castle and later as a surname. Separately, the modern proper name 'Baileys' was adopted as a commercial brand for an Irish cream liqueur.