'intravenous' originates from Latin, specifically the combining elements 'intra-' meaning 'within' and 'vena' meaning 'vein', with the English adjective-forming suffix '-ous'.

'intravenous' changed from Medieval Latin 'intravenosus' (formed from 'intra-' + 'vena') and eventually became the modern English word 'intravenous'.

Initially it meant 'located within a vein' and over time the meaning broadened slightly to include 'administered into a vein' and adjectival uses referring to the venous route.