'non-edematous' is formed in English from the prefix 'non-' (meaning 'not') plus 'edematous'. 'Edematous' originates from Latin 'oedema', which in turn comes from Greek 'oidēma', where 'oidē-'/ 'oidēma' meant 'a swelling'.

'edematous' developed from Medieval Latin/Neo-Latin 'oedema' (from Greek 'oidēma') into English as 'edema'/'oedema' and then the adjective form 'edematous'; the modern English compound 'non-edematous' is created by attaching the negative prefix 'non-' to that adjective.

Initially the root 'oidēma' meant 'a swelling'; over time it yielded English forms referring to swelling ('edema'/'oedema') and adjectives meaning 'having swelling' ('edematous'). The compound 'non-edematous' now means 'not having swelling'.