substitute-n; 3 Senses

Sense Number 1: a person or thing in the role of being a replacement for something else

Commentary: SUBSTITUTE[+relation][+role][+replacement][+entity]

The pink packets contain a sugar substitute, and the white packets contain sugar.
There is just no substitute for real quality.
They'll use a substitute for the star during the action scenes of the film.
You can use raisins as a substitute if you don't have any currants.

WordNet 3.0 Sense Numbers: 1, 3

Sense Number 2: an athlete who is a second-stringer

Commentary: SUBSTITUTE[+entity][+person][+athlete][+second_stringer]

They'll put a substitute in for that batter who can't run the bases so fast.
His brother is the substitute catcher for a major league baseball team.
How many substitutes is each team allowed during a game?

WordNet 3.0 Sense Numbers: 2

Sense Number 3: emotional stand-in for the real object of desire which has been deprived

Commentary: SUBSTITUTE[+relation][+role][+stand_in][+emotional]
NOTE: a specialized, psychological use of Sense 1

Mary's cats are clearly child substitutes in her life.
John realized his boss had become a father substitute for him.

WordNet 0.0 Sense Numbers: 1b