THESAURUS
backup
about-face, about-turn, advocate, agent, alter ego, alternate, alternative, amicus curiae, analogy, attorney, back track, back trail, backing, backing off, backing out, backing up,
backup man, champion, change, changeling, comparison, copy, counterfeit, deputy, double, dummy, equal, equivalent, ersatz, exchange, executive officer, exponent, fake, figurehead, fill-in, ghost, ghostwriter, imitation, lieutenant, locum, locum tenens, makeshift, metaphor, metonymy, mock, next best thing, paranymph, personnel, phony, pinch, pinch hitter, pleader, procurator, provisional, proxy, relief, replacement, representative, reserve, reserves, reversal, reverse, reversing, reversion, right-about, right-about-face, ringer, second in command, second string, secondary, sign, spare, spares, stand-in, stopgap, sub, substituent, substitute, substitution, succedaneum, superseder, supplanter, surrogate, swingaround, symbol, synecdoche, temporary, tentative, third string, token, turnabout, turnaround, understudy, utility, utility man, utility player, vicar, vicar general, vicarious, vice, vice-president, vice-regent, vicegerent, volte-face