'hemangiomatous' originates from New Latin/Modern Latin, specifically from the word 'hemangioma' with the adjective-forming suffix '-ous', where 'haima' (hem-/hemo-) meant 'blood', 'angeion' (angio-) meant 'vessel', and '-oma' meant 'tumor'.

'hemangiomatous' developed from New Latin 'haemangioma' (from Greek 'haima' + 'angeion' + suffix '-oma'), which entered English as 'hemangioma'; adding the English adjective suffix '-ous' produced 'hemangiomatous'.

Initially the roots described 'blood' and 'vessel' and the whole form referred to a 'blood-vessel tumor'; over time the adjective 'hemangiomatous' came to specifically mean 'relating to or characterized by hemangiomas'.