'seer' (prophetic sense) originates from Old English via Middle English: from the verb 'see' (Old English 'seon') with the agentive suffix '-er', producing Middle English forms such as 'seere' or 'siere'. The South Asian unit 'seer' (also spelled 'ser') entered English later via Hindi/Urdu 'ser'/'seer' during the British colonial period.

The prophetic sense changed from Middle English 'seere'/'siere' into modern English 'seer'. The unit sense was borrowed into English from Hindi/Urdu 'ser' (also rendered 'seer') and was anglicized in usage and spelling in colonial accounts.

Initially a literal 'one who sees' (from the verb 'see'), the word came to denote specifically a 'prophet' or someone with prophetic/clairvoyant insight. The unit sense originally named a regional measure in South Asia and retained that specific meaning in historical contexts.