Substitute \Sub"stit"ute\, v. t. [imp. & p. p. Substituted; p. pr. & vb. n. Substituting.]

[See Substitute, n.]

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.

Source: Webster's Revised Unabridged Dictionary (1913)
 

Substitute \Sub"stit"ute\, n. [L. substitutus, p. p. of substituere to put under, put in the place of; sub under + statuere to put, place: cf. F. substitut. See Statute.]

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

Source: Webster's Revised Unabridged Dictionary (1913)