'antibaryon' originates from the Modern English combination of the prefix 'anti-' (from Greek 'anti-' meaning 'against, opposite') and 'baryon' (from Greek 'barys' meaning 'heavy'), used in particle physics to denote the counterpart of a baryon.

'baryon' was adopted into physics terminology in the mid-20th century from Greek 'barys' ('heavy') via New Latin/Modern scientific coinage; 'antibaryon' formed later by adding the productive scientific prefix 'anti-' to denote the antiparticle of a baryon.

Initially 'barys' meant 'heavy' in Greek; in modern physics 'baryon' denotes a class of hadrons (originally referring to relatively massive particles), and 'antibaryon' now specifically means the antiparticle with opposite baryon number.