'hemodilution' originates from Greek via New Latin and English combining forms: 'hemo-' (from Greek 'haima' meaning 'blood') combined with 'dilution' (from Latin 'dilutio'/'diluere', meaning 'to wash away' or 'to dilute').

'hemodilution' developed as a compound in modern medical English (20th century) from the combining form 'hemo-' + English noun 'dilution'; the British spelling 'haemodilution' reflects the Greek-based 'haemo-' spelling and coexisted with the simplified 'hemodilution'.

Initially it literally meant 'dilution of blood'; over time it has retained that basic meaning but broadened to refer also to specific clinical techniques and procedures (e.g., acute normovolemic hemodilution).