'euvolemic' originates from a modern medical formation combining Greek 'eu-' (meaning 'good' or 'well') and New Latin/modern combining form 'volemia' (from Latin 'volumen' meaning 'volume').

'euvolemic' was formed in modern medical English from New Latin 'euvolemia' (the noun form), itself built from Greek 'eu-' + a formation related to Latin 'volumen' ('volume'), and adapted into English usage in the 20th century in clinical contexts.

Initially it denoted 'having an appropriate (adequate) blood volume'; this core meaning has been retained and is used today to mean 'normal blood/intravascular volume.'