1.a person or thing that takes or can take the place of another
2.an athlete who plays only when another member of the team drops out
3.someone who takes the place of another (as when things get dangerous or difficult);
the star had a stand-in for dangerous scenes
4.being a replacement or substitute for a regular member of a team
5.capable of substituting in any of several positions on a team;
a utility infielder
6.artificial and inferior;
ersatz coffee
1.put in the place of another; switch seemingly equivalent items;
the con artist replaced the original with a fake Rembrandt
2.be a substitute;
The young teacher had to substitute for the sick colleague
3.act as a substitute;
She stood in for the soprano who suffered from a cold