'theory-oriented' originates from the combination of 'theory' and 'oriented', where 'theory' comes from the Greek word 'theoria', meaning 'contemplation, speculation', and 'oriented' is derived from the Latin 'orientare', meaning 'to arrange or align'.

'theory' changed from the Greek word 'theoria' and eventually became the modern English word 'theory'. 'Oriented' evolved from the Latin 'orientare' through Old French 'orienter'.

Initially, 'theory' meant 'contemplation or speculation', but over time it evolved into its current meaning of 'a system of ideas intended to explain something'.