At pleasure. / At will. / To whatever extent. / Extemporaneously.

Extemporaneous, impromptu.

To perform without script. / To perform without preparation. / To perform extemporaneously.

To improvise all or part of a speech or other performance, especially in comedy.

present participle of ad-lib

simple past tense and past participle of ad-lib

Improvised, or performed without preparation.

plural of ad-lib

simple past tense and past participle of ad lib

present participle of ad lib