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