'antitrypsin' is formed from the prefix 'anti-' (from Greek anti, meaning 'against') combined with 'trypsin' (from Greek τρυψίνη trupsínē, the name of a digestive protease).

'trypsin' entered scientific usage from Greek via New Latin ('trypsinum'); the compound term 'antitrypsin' was coined in the 20th century in medical/biochemical literature by combining 'anti-' + 'trypsin'.

Initially used in a general sense for any inhibitor acting against trypsin, the term has come to be most commonly associated with the specific serum protein 'alpha-1-antitrypsin' in clinical contexts.