'antiproton' originates from modern English, formed from the prefix 'anti-' (from Greek anti- meaning 'against' or 'opposite') and 'proton' (from Greek protos meaning 'first'), where 'anti-' meant 'opposite' and 'proton' referred to the primary particle 'proton'.

'antiproton' developed as a compound of 'anti-' + 'proton' in the 20th century with the rise of particle physics; 'proton' itself comes from Greek 'protos' via New Latin 'proton', and the compound solidified from forms like 'anti-proton' into the single word 'antiproton' as usage standardized after the particle's experimental discovery in 1955.

Initially coined as a theoretical 'opposite of a proton', the term became the established name for the physical antiparticle observed and characterized experimentally; its meaning narrowed to this specific particle.