1. (n.) One who, or that which, is left or taken in the place of another, as a child exchanged by fairies.

2. (n.) A simpleton; an idiot.

3. (n.) One apt to change; a waverer.

4. (a.) Taken or left in place of another; changed.

5. (a.) Given to change; inconstant.

agent alternate alternative analogy backup change comparison copy counterfeit deputy double dummy elf child equal equivalent ersatz exchange fake fill-in ghost ghostwriter imitation locum tenens makeshift metaphor metonymy next best thing personnel phony pinch hitter proxy relief replacement representative reserves ringer second string secondary sign spares stand-in sub substituent substitute substitution succedaneum superseder supplanter surrogate symbol synecdoche third string token understudy utility player vicar vice-president vice-regent