'vehicle-mandatory' is a compound word formed from 'vehicle' and 'mandatory'. 'Vehicle' originates from Latin, specifically the word 'vehiculum', where 'vehere' meant 'to carry'. 'Mandatory' comes from Latin 'mandatorius', derived from 'mandare', meaning 'to order'.

'Vehicle' evolved from the Latin 'vehiculum' through Old French 'vehicule', and 'mandatory' evolved from Latin 'mandatorius' through Old French 'mandatorie'.

Initially, 'vehicle' referred to any means of transport, and 'mandatory' meant 'ordered'. Together, they now refer to something required for vehicles.