'normovolemia' originates from New Latin/modern medical formation, specifically the prefix 'normo-' from Latin 'norma', where 'norma' meant 'rule, standard', and the element 'volemia' from Neo-Latin formation related to Latin 'volumen' (via medical coinage) where 'volumen' meant 'volume'.

'normovolemia' was formed in modern medical Latin by combining 'normo-' + 'volemia' and entered English medical usage in the 20th century as a technical term for normal blood volume.

Initially it meant 'standard/normal volume (of blood)', and this meaning has remained essentially unchanged in medical usage.