'antibacterial' originates from the prefix 'anti-' from Greek 'anti' meaning 'against' combined with 'bacterial', ultimately from New Latin 'bacterium' (from Greek 'bakterion'), where 'bakterion' meant 'small staff' (a diminutive of 'bakteria' meaning 'staff').

'antibacterial' formed in English by combining 'anti-' and 'bacterial' in the 20th century as medical terminology expanded; 'bacterium' itself entered English via New Latin from Greek 'bakterion', and over time the combined form settled as 'antibacterial' and its plural 'antibacterials'.

Initially constructed to mean 'against bacteria', it has retained that core meaning while broadening to refer both to agents (substances) and properties (adjective use) that act on bacteria.