What is the meaning of substitute?

noun

• A person or thing that takes or can take the place of another.
  • synonyms: replacement
• An athlete who plays only when a starter on the team is replaced.
  • synonyms: reserve, second-stringer
• Someone who takes the place of another (as when things get dangerous or difficult. )
  • usage: "the star had a stand-in for dangerous scenes"; "we need extra employees for summer fill-ins"
  • synonyms: stand-in, relief, reliever, backup, backup man, fill-in

verb

• Put in the place of another; switch seemingly equivalent items.
  • usage: "the con artist replaced the original with a fake Rembrandt"; "substitute regular milk with fat-free milk"; "synonyms can be interchanged without a changing the context's meaning"
  • synonyms: replace, interchange, exchange
• Be a substitute.
  • usage: "The young teacher had to substitute for the sick colleague"; "The skim milk substitutes for cream-we are on a strict diet"
  • synonyms: sub, stand in, fill in
• Act as a substitute.
  • usage: "She stood in for the soprano who suffered from a cold"
  • synonyms: deputize, deputise, step in

adjective

• Capable of substituting in any of several positions on a team.
  • usage: "a utility infielder"
  • synonyms: utility
• Serving or used in place of another.
  • usage: "an alternative plan"
  • synonyms: alternate, alternative
• Artificial and inferior.
  • usage: "ersatz coffee"; "substitute coffee"
  • synonyms: ersatz