What is the meaning of Substitute?

To use in place of something else, with the same function.

To use X in place of Y.

To use Y in place of X; to replace X with Y.

To remove (a player) from the field of play and bring on another in his place.

To serve as a replacement (for someone or something).

A replacement or stand-in for something that achieves a similar result or purpose.

A player who is available to replace another if the need arises, and who may or may not actually do so.

One who enlists for military service in the place of a conscript.

Source: wiktionary.org

See also