'barmaster' is a compound of 'bar' and 'master'. 'bar' originates from Middle English and Old French 'barre' meaning 'bar' or 'barrier' (a counter or barrier where drinks are served), and 'master' originates from Old English via Old French from Latin 'magister' meaning 'teacher' or 'chief'.

'bar' originally referred to a barrier or counter and by extension the place where drinks are served; 'master' came from Latin 'magister' through Old French and Old English. The compound 'barmaster' formed in modern English by combining these elements to denote the chief person in charge of a bar.

Initially, 'master' meant 'teacher' or 'chief' and 'bar' meant 'counter' or 'barrier'; combined as 'barmaster' it meant 'the chief of the bar' and has retained the sense of a person in charge of bar operations.