'atraumatic' originates from Modern English formation, specifically from the prefix 'a-' (from Greek 'ἀ-' meaning 'not') combined with 'traumatic', which ultimately comes from Greek 'τραῦμα' where 'τραῦμα' meant 'wound'.

'atraumatic' changed by adding the negative prefix 'a-' to 'traumatic' (itself derived into English via Latin/French from Greek 'τραῦμα') and eventually became the modern English medical adjective 'atraumatic'.

Initially it meant 'not causing a wound', but over time it evolved into the broader modern sense 'causing little or no physical (or procedural) injury', especially in medical contexts.