'autocoprophagous' originates from Modern scientific English, formed from Greek combining elements: 'auto-' from Greek 'autos' meaning 'self', 'kopros' meaning 'dung', and 'phagein' meaning 'to eat'.

'autocoprophagous' is a modern compound built on the older formation 'coprophagous' (from Greek 'kopros' + 'phagein'), with the prefix 'auto-' added to specify 'self-'; 'coprophagous' entered scientific English in the 19th century and 'autocoprophagous' is a later, more specific formation.

Initially related terms described general feces-eating behavior; the compound with 'auto-' specifically came to mean 'eating one's own feces', a more precise sense used in medical, veterinary, and biological contexts.