ad-lib

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

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-lib·bing.

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

adjective

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

noun

1. something improvised in speech, music, etc.: Was that joke part of your speech or an ad lib?

adverb

2. at one’s pleasure; without restriction.
3. freely; as needed; without stint: Water can be given to the patients ad lib.

1. ad libitum.

verb -libs, -libbing or -libbed

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

adjective (ad lib when predicative)

2. improvised; impromptu

adverb ad lib

3. without restraint; freely
4. music short for ad libitum

noun

5. an improvised performance, often humorous

1811, shortened from Latin ad libitum “at one’s pleasure, as much as one likes” (c.1600), from libere “to please” (see libido). First recorded as one word 1919 (v.), 1925 (n.).

abbr.

1. ad libitum (freely, as desired)