'reservation' originates from Latin, specifically the word 'reservare', where 're-' meant 'back/again' and 'servare' meant 'to keep/save'.

'reservation' passed into Middle French/Old French as 'reservation'/'reserver' and then into Middle English as 'reservacioun' before becoming the modern English 'reservation'.

Initially, it meant 'the act of keeping back or withholding'; over time it evolved to include 'the act of setting something aside for future use' and the figurative sense of 'doubt or hesitation'.