'appertain' originates from Latin via Old French and Middle English; it is ultimately from Latin 'pertinēre' where 'per-' meant 'through' or 'completely' and 'tenēre' meant 'to hold'.

'appertain' entered English from Anglo-Norman/Old French forms such as 'apartenir' and Middle English 'aperten' and developed into the modern English 'appertain'.

Initially, the root meant 'to reach or extend to' (from Latin 'pertinēre'); over time this evolved into the current sense of 'to belong to, concern, or be applicable to'.