[ad-lib, ad-]

verb (used with object), ad-libbed, ad-lib·bing.

to improvise all or part of (a speech, a piece of music, etc.): to ad-lib one's lines.

verb (used without object), ad-libbed, ad-lib·bing.

to act, speak, etc., without preparation: Throughout the play he had to ad-lib constantly.


impromptu; extemporaneous: ad-lib remarks to hecklers.

Nearby words

  1. ad valorem tax,
  2. ad verbum,
  3. ad vitam,
  4. ad vivum,
  5. ad-,
  6. ad.,
  7. ada,
  8. ada deficiency,
  9. adabazar,
  10. adactylous

Origin of ad-lib

1915–20, Americanism; v. use of ad lib

Related formsad-lib·ber, noun Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019

British Dictionary definitions for adlibbing


verb -libs, -libbing or -libbed

to improvise and deliver without preparation (a speech, musical performance, etc)

adjective (ad lib when predicative)

improvised; impromptu

adverb ad lib

without restraint; freely
music short for ad libitum


an improvised performance, often humorous
Derived Formsad-libber, noun

Word Origin for ad-lib

C18: short for Latin ad libitum, literally: according to pleasure

Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012