'beta-hemolytic' originates from Modern English, combining 'beta' (from Greek 'beta', the second letter) and 'hemolytic' (from New Latin 'haemolyticus', itself from Greek 'haima' meaning 'blood' and 'lytikos' meaning 'able to loosen or dissolve').

'hemolytic' entered English via New Latin 'haemolyticus' (from Greek 'haima' + 'lytikos'), while 'beta' comes from the name of the Greek letter 'beta'; together they formed the compound adjective 'beta-hemolytic' in medical/microbiological usage.

Initially the roots referred generally to 'blood' ('haima') and 'loosening/dissolving' ('lytikos'); over time the compound came to mean specifically 'causing complete lysis of red blood cells (on agar)', a precise microbiological characteristic.