substitute

American Heritage® Dictionary of the English Language, Fourth Edition

1. n. One that takes the place of another; a replacement: "Fantasies are more than substitutes for unpleasant reality” ( Barbara Grizzuti Harrison).
2. n. Grammar A word or construction used in place of another word, phrase, or clause.
3. v. To put or use (a person or thing) in place of another: "substituting moral power for physical force” ( Elizabeth Cady Stanton).
4. v. Chemistry To replace (one or more elements or radicals in a compound) by other elements or radicals.
5. v. To take the place of another: "Only art can substitute for nature” ( Leonard Bernstein).

Century Dictionary and Cyclopedia

1. To put in the place of another; put in exchange.
2. To appoint; invest with delegated authority.
3. Put in the place or performing the functions of another; substituted.
4. n. A person put in the place of another; one acting for or in the room of another; theatrical, an understudy; specifically (military), one who for a consideration serves in an army or navy in the place of a conscript; also, a thing serving the purpose of another.
5. n. In calico-printing, a solution of phosphate of soda and phosphate of lime with a little glue or other form of gelatin, used as a substitute for cow-dung.
6. n. Synonyms Proxy, alternate.
7. In chem., to replace (an atom or group) in the molecule of a compound by another atom or group. See substituent.

Wiktionary

1. v. transitive To use in place of something else, with the same function.
2. v. transitive In the phrase "substitute X for Y", to use X in place of Y.
3. v. transitive In the phrase "substitute X with/by Y", to use Y in place of X.
4. v. transitive, sports To remove (a player) from the field of play and bring on another in his place.
5. v. intransitive To serve as a replacement (for someone or something)
6. n. A replacement or stand-in for something that achieves a similar result or purpose.
7. n. sports A player who is available to replace another if the need arises, and who may or may not actually do so.

GNU Webster's 1913

1. n. (Mil.) 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. a person who enlists for military service in the place of a conscript or drafted man.
2. v. To put in the place of another person or thing; to exchange.

WordNet 3.0

1. adj. capable of substituting in any of several positions on a team
2. adj. serving or used in place of another
3. n. a person or thing that takes or can take the place of another
4. n. someone who takes the place of another (as when things get dangerous or difficult)
5. v. put in the place of another; switch seemingly equivalent items
6. adj. artificial and inferior
7. v. act as a substitute
8. v. be a substitute
9. n. an athlete who plays only when a starter on the team is replaced