Definitions

1. noun

a person or thing that takes the place of another

“The substitute teacher helped the students with their homework.”

2. verb

to put or use something in place of another

“We had to substitute the broken part with a new one.”

3. verb

to act or serve as a replacement for someone or something

“She substituted for her sister in the play.”

4. verb

to replace or exchange something, especially in a game

“I substituted my card with a new one in the poker game.”