'arginase' originates from the amino acid name 'arginine' combined with the enzyme-forming suffix '-ase' (from New Latin/French), where 'arginine' ultimately derives from Greek 'argyros' meaning 'silver' (referring to the silvery appearance of its crystalline form).

'arginase' was formed in modern biochemical nomenclature by adding the suffix '-ase' to 'arginine', following the late 19th/early 20th century convention for naming enzymes (e.g., 'diastase' → '-ase' productive suffix).

Initially coined to denote the enzyme acting specifically on arginine, the term's meaning has remained stable and continues to refer to that catalytic activity in modern biochemistry.