Substitute

Part of speech: noun (n.)

1. 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; specifically (Mil.),

2. a person who enlists for military service in the place of a conscript or drafted man. Hast thou not made me here thy substitute Milton. Ladies [in Shakespeare's age] . . . wore masks as the sole substitute known to our ancestors for the modern parasol. De Quincey.

Part of speech: verb (v.)

To put in the place of another person or thing; to exchange. Some few verses are inserted or substituted in the room of others. Congreve.