substitute

Concise Oxford English Dictionary © 2008 Oxford University Press:
substitute/ˈsʌbstɪtjuːt/

▶noun

• 1 a person or thing acting or serving in place of another.

• 2 a sports player nominated as eligible to replace another after a match has begun.

• 3 Scots Law a deputy.

▶verb

• 1 (usu. substitute something for) use, add, or serve in place of.

  ■ (usu. substitute something with) replace with another.

  ■ Chemistry replace (an atom or group in a molecule) with another.

• 2 replace (a sports player) with a substitute during a match.

– derivatives
substitutability noun,
substitutable adjective,
substitutive adjective.

– origin ME (denoting a deputy or delegate): from L. substitut-, substituere ‘put in place of’.

usage: Traditionally, the verb substitute is followed by for and means ‘put (someone or something) in place of another’, as in she substituted the fake vase for the real one. More recently it has also been used with with or by to mean ‘replace (something) with something else’, as in she substituted the real vase with the fake one. Though still disapproved of by traditionalists, this use is now generally regarded as part of standard English.