'terrain-adjustable' originates from the combination of 'terrain' and 'adjustable'. 'Terrain' comes from Latin 'terra', meaning 'earth', and 'adjustable' comes from the verb 'adjust', which originates from Old French 'ajuster', meaning 'to bring into line'.

'Terrain' evolved from Latin 'terra' through Old French 'terrein', while 'adjustable' evolved from Old French 'ajuster'. The combination of these words into 'terrain-adjustable' is a modern English creation.

Initially, 'terrain' referred to 'land or ground', and 'adjustable' meant 'capable of being adjusted'. The combined term 'terrain-adjustable' specifically refers to the ability to adapt to different land conditions.