verb, -libbed, -lib⋅bing, adjective | 1. | to improvise all or part of (a speech, a piece of music, etc.): to ad-lib one's lines. |
| 2. | to act, speak, etc., without preparation: Throughout the play he had to ad-lib constantly. |
| 3. | impromptu; extemporaneous: ad-lib remarks to hecklers. |