'protohuman' originates from the Greek prefix 'proto-' (from Greek 'prôtos') meaning 'first, earliest', combined with English 'human', ultimately from Latin 'humanus' meaning 'of man'.

'proto-' comes from Greek 'prôtos' meaning 'first'; 'human' derives from Latin 'humanus' (via Old French and Middle English). The compound 'protohuman' appears in modern scientific English (19th–20th century) to describe early human ancestors or human-like primates.

Initially it carried the literal sense 'first human' or 'first of the human line', and over time it has come to be used more broadly for early ancestors, human-like hominins, or things resembling primitive humans.