Meaning : An athlete who plays only when a starter on the team is replaced.
Synonyms : reserve, second-stringer
Meaning : Put in the place of another. Switch seemingly equivalent items.
Example :
The con artist replaced the original with a fake Rembrandt.
Substitute regular milk for fat-free milk.
Synonyms can be interchanged without a changing the context's meaning.
Synonyms : exchange, interchange, replace
Meaning : Capable of substituting in any of several positions on a team.
Example :
A utility infielder.
Synonyms : utility
Meaning : Serving or used in place of another.
Example :
An alternative plan.
Synonyms : alternate, alternative