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

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

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

Full Definition of SUBSTITUTION

a :  the act, process, or result of substituting one thing for another
b :  replacement of one mathematical entity by another of equal value
:  one that is substituted for another
sub·sti·tu·tion·al \-shnəl, -shə-nəl\ adjective
sub·sti·tu·tion·al·ly adverb
sub·sti·tu·tion·ary \-shə-ˌner-ē\ adjective


  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.


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 Kids

:  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

:  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
a :  the turning from an obstructed desire to another desire whose gratification is socially acceptable b :  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>
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