'pet-occupied' originates from English, specifically the words 'pet' and 'occupied', where 'pet' originally meant 'tame animal' and 'occupied' ultimately comes from Latin 'occupare' meaning 'to take possession of'.

'occupied' evolved from Latin 'occupare' into Old French and then Middle English forms before becoming modern English 'occupied'; 'pet' comes from Middle English 'pet' (of uncertain earlier origin) and retained the meaning 'tame or domesticated animal', and the compound form 'pet-occupied' is a modern English formation combining these elements.

Initially 'occupied' meant 'taken up or seized'; over time it broadened to mean 'inhabited or used by', so in compounds like 'pet-occupied' it now means 'inhabited by pets'.