1. (n.) One who, or that which, is substituted or put in the place of another; one who acts for another; that which stands in lieu of something else

2. (n.) a person who enlists for military service in the place of a conscript or drafted man.

3. (n.) To put in the place of another person or thing; to exchange.

additional advocate agent alter ego alternate alternative amicus curiae analogy another attorney backup backup man bit player champion change change for changeling commute comparison compound for copy counterfeit delegate deputy dernier ressort displace double double for dub in dummy equal equivalent ersatz exchange executive officer expediency expedient exponent extra fake FALSE father figure father image figurant figurante figurehead fill-in ghost ghostwriter give place to imitation lieutenant locum locum tenens make do with make way for makeshift metaphor metonymy mock mother figure mother surrogate mute next best thing offer in exchange other paranymph personnel phony pinch pinch hitter pinch-hit for pleader procurator provisional proxy put up with recourse redeem refuge relay relief relieve replace replacement representative reserve reserves resort ring in ringer second second in command second string secondary sham shift with sign simulated spare spares spear-carrier spurious stand in for stand-in standby stopgap sub substituent substitute for substitution succedaneum supe super supernumerary superseder supplant supplanter supplemental supplementary supply support supporting actor supporting cast surrogate swap switch symbol synecdoche take in exchange temporary tentative third string token trade understudy utility utility man utility player vicar vicar general vicarious vice vice-president vice-regent vicegerent walk-on walking gentleman