designated driver(n = noun.person) - the member of a party who is designated to refrain from alcohol and so is sober when it is time to drive home;
is a kind of driver

N  temperance, moderation, sobriety, soberness, forbearance, abnegation, self-denial, self-restraint, self-control, frugality, vegetarianism, teetotalism, total abstinence, abstinence, abstemiousness, Encratism, prohibition, system of Pythagoras, system of Cornaro, Pythagorism, Stoicism, vegetarian, Pythagorean, gymnosophist, teetotaler, abstainer, designated driver, Encratite, fruitarian, hydropot, temperate, moderate, sober, frugal, sparing, abstemious, abstinent, within compass, measured, on the wagon, on the water wagon, dry, Pythagorean, vegetarian, teetotal, appetitus rationi obediant, l'abstenir pour jouir c'est l'epicurisme de la rai, trahit sua quemque voluptas.

automobile driver, backseat driver, bus driver, designated, designated hitter, device driver, driver, driver ant, engine driver, hack driver, livery driver, mule driver, pile driver, race driver, slave driver, stake driver, sunday driver, tank driver, test driver, truck driver