'hyperemia' originates from Greek via New Latin/medical Latin: the Greek prefix 'hyper-' meaning 'over, above' combined with Greek 'haima' meaning 'blood' (rendered in medical formation as '-emia').

'hyperemia' entered English medical usage from New Latin/late Latin formations (e.g. New Latin 'hyper(a)emia'), itself modelled on Greek elements 'hyper-' + 'haima'; the British spelling 'hyperaemia' reflects that formation and historical spelling conventions.

Initially it referred to an excess of blood in a part of the body (from the Greek elements 'over' + 'blood'); this core meaning has been retained in modern medical usage, though distinctions such as 'active' vs 'passive' hyperemia have been developed.