Merriam-Webster Logo
  • Dictionary
  • Thesaurus
  • Scrabble
  • Spanish Central
  • Learner's Dictionary


noun sub·sti·tu·tion \ˌsəb-stə-ˈtü-shən, -ˈtyü-\

Simple Definition of substitution

  • : the act of substituting or replacing one person or thing with another

  • : someone or something that is or can be substituted for another

Source: Merriam-Webster's Learner's Dictionary

Full Definition of substitution

  1. 1a :  the act, process, or result of substituting one thing for anotherb :  replacement of one mathematical entity by another of equal value

  2. 2 :  one that is substituted for another

substitutional play \-shnəl, -shə-nəl\ adjective
substitutionally adverb
substitutionary play \-shə-ˌner-ē\ adjective

Examples of substitution in a sentence

  1. The coach made three substitutions in the second half of the game.

  2. I'd prefer rice with my steak instead of potatoes, but the menu says no substitutions.

  3. Substitution of applesauce for oil is one way of reducing the fat in recipes.

  4. The cookbook has a long list of substitutions for ingredients that may be hard to find.

Origin of substitution

Middle English substitucion, from Middle French, from Late Latin substitution-, substitutio, from substituere

First Known Use: 14th century

SUBSTITUTION Defined for Kids


noun sub·sti·tu·tion \ˌsəb-stə-ˈtü-shən, -ˈtyü-\

Definition of substitution for Students

  1. :  the act or process of putting in or taking the place of another

Medical Dictionary


noun sub·sti·tu·tion \ˌsəb-stə-ˈt(y)ü-shən\

Medical Definition of substitution

  1. 1:  a chemical reaction in which one or more atoms or groups in a molecule are replaced by equivalent atoms or groups to form at least two products; especially :  the replacement of hydrogen in an organic compound by another element or group

  2. 2a:  the turning from an obstructed desire to another desire whose gratification is socially acceptableb:  the turning from an obstructed form of behavior to a different and often more primitive expression of the same tendency <a substitution neurosis>c:  the reacting to each of a set of stimuli by a response prescribed in a key <a substitution test for speed of learning new responses>

Law Dictionary


noun sub·sti·tu·tion \ˌsəb-stə-ˈtü-shən, -ˈtyü-\

Legal Definition of substitution

  1. :  the substituting of one person or thing for another: as a in the civil law of Louisiana :  a disposition not in trust by which a donee, heir, or legatee is charged to hold property transferred and return it to a third person — compare fidei commissum, vulgar substitution Editor's note: Substitutions are prohibited. b :  replacement of a party to an action with a successor or representative upon motion to the court when the party is unable to continue litigating (as because of death, incompetency, transfer of interest, or loss of the office for which the party was suing or being sued in an official capacity) c :  the replacement of a new agreement or obligation for an old one — see also novation

substitutional \-shə-nəl\ play adjective
substitutionary \-shə-ˌner-ē\ play adjective

Seen and Heard

What made you want to look up substitution? Please tell us where you read or heard it (including the quote, if possible).


the range of perception or understanding

Get Word of the Day daily email!


Take a 3-minute break and test your skills!


Which of these is a synonym of nonplus?

soothe reduce disapprove perplex
Name That Thing

Test your visual vocabulary with our 10-question challenge!


Test Your Knowledge - and learn some interesting things along the way.