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Synonyms

ad lib

1 American  
[ad lib, ad] / æd ˈlɪb, ˈæd /

noun

  1. something improvised in speech, music, etc..

    Was that joke part of your speech or an ad lib?

adverb

  1. at one's pleasure; without restriction.

  2. freely; as needed; without stint.

    Water can be given to the patients ad lib.
ad lib. 2 American  

abbreviation

  1. ad libitum.

ad-lib 3 American  
[ad-lib, ad-] / ædˈlɪb, ˈæd- /

verb (used with object)

ad-libbed, ad-libbing

  1. 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-libbing

  1. to act, speak, etc., without preparation.

    Throughout the play he had to ad-lib constantly.

adjective

  1. impromptu; extemporaneous.

    ad-lib remarks to hecklers.
ad-lib British  
/ ædˈlɪb /

verb

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

"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

adjective

  1. improvised; impromptu

"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

adverb

  1. without restraint; freely

  2. music short for ad libitum

"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

noun

  1. an improvised performance, often humorous

"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

Other Word Forms

  • ad-libber noun

Etymology

Origin of ad lib1

First recorded in 1810–20; ad libitum

Origin of ad-lib3

1915–20, v. use of ad lib

Vocabulary lists containing ad-lib

Reading: Literature - Drama - Introductory

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Theater - Introductory

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Reading: Literature - Drama - Middle School

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Example Sentences

Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.

“It’s a spill-your-guts-out record,” she says, adding that for every song, she’d write a first verse, then ad lib the rest in the studio.

From Los Angeles Times • Aug. 6, 2025

They sang every word, every ad lib, of every song - some with mascara running, others with hands clasped to their chests.

From BBC • Sep. 13, 2024

Sure enough, after three months, the mice who ate ad lib were stricken with obesity, diabetes, liver disease, and a host of other ugly conditions.

From Salon • Oct. 9, 2022

We shoot six episodes a day and they just fly along because it’s all ad lib.

From Seattle Times • Sep. 13, 2021

There is a silence in the room and then a babble of ad lib conversation. 9TH JUROR: Please.

From "Twelve Angry Men" by Reginald Rose

Definitions and idiom definitions from Dictionary.com Unabridged, based on the Random House Unabridged Dictionary, © Random House, Inc. 2023

Idioms from The American Heritage® Idioms Dictionary copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.