substitute

verb

1. (transitive)To use in place of something else, with the same function.

   “I had no shallots so I substituted onion.”

2. (transitive)To use X in place of Y.

   “I had to substitute new parts for the old ones.”

3. (transitive)To use Y in place of X; to replace X with Y.

   “I had to substitute old parts with the new ones.”

   “You know when you first have a baby, and you're like "I'm gonna die 'cause I've never slept"? … and you get [an] hour and a half in the middle of the night that you get to sleep. Your partner's like, "I'll take care of this." … I used that hour and a half, instead of sleeping, to watch The Pitt. … The most panic inducing show. … I was just like I was like, "Why do I feel like vomiting 24/7? Oh, I substituted sleep for watching The Pitt."”

4. (transitive)To remove (a player) from the field of play and bring on another in his place.

   “He was playing poorly and was substituted after twenty minutes”

   “Mario Balotelli replaced Tevez but his contribution was so negligible that he suffered the indignity of being substituted himself as time ran out, a development that encapsulated a wretched 90 minutes for City and boss Roberto Mancini.”

5. (intransitive)To serve as a replacement (for someone or something).

   “Accumulation of wealth by this route may substitute for personal saving.”

noun

1. A replacement or stand-in for something that achieves a similar result or purpose.

   “Ladies [in William Shakespeare's age], again, universally wore masks as the sole substitute known to our ancestors for the modern parasol; a fact, perhaps, not generally known.”

   “Since you left me, if you see me with another girl / Seeming like I'm having fun / Although she may be cute, she's just a substitute / Because you're the permanent one”

   “No other love before / Could do what you do / A little so much (Oh) / So much more from you / No one else will do / There's no substitute / Your love's the finest love I've ever known / Ooh-ooh-ooh”

   “Here we go. AK-47. The very best there is. When you absolutely, positively got to kill every motherfucker in the room, accept no substitutes.”

2. A substitute teacher.
3. A player who is available to replace another if the need arises, and who may or may not actually do so.

   “Dean Whitehead opened the scoring shortly after the break with a low finish and substitute Peter Crouch sealed the win with a tap-in.”

4. (historical)One who enlists for military service in the place of a conscript.
5. (abbreviation, alt-of)Abbreviation of substitute good.