ad lib

UK: /ædˈlɪb/ US: /æd ˈlɪb, ˈæd/ ,(ad lib′, ad′)

Inflections of 'ad lib' (v): (⇒ conjugate)

ad-libs

v 3rd person singular

ad-libbing

v pres p

ad-libbed

v past

ad-libbed

v past p

WordReference Random House Learner's Dictionary of American English © 2026

ad lib /æd ˈlɪb, ˈæd/  adv. 

1. freely and without prior planning:
   added a few remarks ad lib.

ad-lib /æd ˈlɪb, ˈæd-/   v., -libbed, -lib•bing, adj. 
v. 

1. to improvise all or part of (a speech, a piece of music, etc.): [~ + object]
   He ad-libbed his speech.
   [no object]
   He ad-libbed for an hour.

adj. 

2. unrehearsed;
   impromptu:
   ad-lib remarks.

ad--lib•ber, n. [countable]

WordReference Random House Unabridged Dictionary of American English © 2026

ad lib  (ad lib′, ad′), 

1. something improvised in speech, music, etc.:
   Was that joke part of your speech or an ad lib?
2. at one's pleasure;
   without restriction.
3. freely;
   as needed;
   without stint:
   Water can be given to the patients ad lib.

• see ad libitum 1810–20

ad-lib  (ad lib′, ad′-), v., -libbed, -lib•bing, adj. 
v.t. 

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

v.i. 

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

adj. 

3. impromptu;
   extemporaneous:
   ad-lib remarks to hecklers.

• verb, verbal use of ad lib 1915–20, American.

ad-lib′ber, n. 

ad lib., 

1. See ad libitum. 

Collins Concise English Dictionary © HarperCollins Publishers::

ad-lib / ædˈlɪb/ verb ( -libs, -libbing, -libbed)

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

adjective (ad lib when predicative)

1. improvised; impromptu

adverb ad lib

1. without restraint; freely
2. short for ad libitum

noun

1. an improvised performance, often humorous

Etymology: 18th Century: short for Latin ad libitum, literally: according to pleasure