'attornment' originates from Anglo-French/Old French, specifically the verb 'atorner' (also attorn in Middle English), where the element 'a(d)-' meant 'to/toward' and the root 'torner/turner' meant 'to turn or appoint'.

'attornment' changed from Middle English 'attornement' (from Anglo-French 'atornement'/'atorner') and eventually became the modern English word 'attornment'.

Initially, it meant roughly 'the act of turning to or appointing' (a more general idea of assignment or appointment); over time it specialized into the legal sense of 'the tenant's formal recognition of a new landlord' now used in property and tenancy law.