ad-libber Definition

ad-lib
verb, tr & intr ad-libbed, ad-libbing

1. To say something without preparation, especially as a departure from a prepared text or to fill time.

Thesaurus: improvise, extemporize, make up.
2. To improvise (music, etc).

adj

1. Said of speeches, etc: made up as the speaker speaks; improvised.

Thesaurus: extemporaneous, spontaneous, off-the-cuff, unrehearsed, ad hoc.

adverb

1. Without preparation.
2. colloq
Without limit; freely.

Derivative: ad-libber
noun

Derivative: ad-libbing
noun

Etymology: 19c as adverb; 20c otherwise: short for Latin ad libitum at pleasure.