SynonymDefinitionAntonym.com - English Synonym Dictionary

A person or thing that takes or can take the place of another

Someone who takes the place of another (as when things get dangerous or difficult)

An athlete who plays only when a starter on the team is replaced

Put in the place of another; switch seemingly equivalent items

Be a substitute

Act as a substitute

Artificial and inferior

Serving or used in place of another

Capable of substituting in any of several positions on a team