'euhydration' originates from Greek, specifically the prefix 'eu-' and the word 'hydor', where 'eu-' meant 'good/well' and 'hydor' meant 'water', combined with the English suffix '-ation' meaning 'process or state'.

'euhydration' was formed in modern medical English by combining the Greek elements 'eu-' + 'hydration' (hydration itself from Greek 'hydor' via Latin/Greek roots); the compound appears in 20th-century clinical literature to denote a normal hydration state.

Initially the components conveyed the idea of a 'good/well water' condition; over time the compound came to be used as a technical term meaning 'normal body water balance' in clinical and physiological contexts.