v. ad-libbed, ad-lib·bing, ad-libs
To improvise and deliver extemporaneously: ad-lib a comic monologue.
To engage in improvisation, as during delivery of a speech.
Words, music, or actions uttered, performed, or carried out extemporaneously.
Uttered, performed, or carried out spontaneously: heckled the speaker with ad-lib comments.
The American Heritage® Dictionary of the English Language, Fifth Edition copyright ©2020 by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
Indo-European & Semitic Roots Appendices
Thousands of entries in the dictionary include etymologies that trace their origins back to reconstructed proto-languages. You can obtain more information about these forms in our online appendices:
The Indo-European appendix covers nearly half of the Indo-European roots that have left their mark on English words. A more complete treatment of Indo-European roots and the English words derived from them is available in our Dictionary of Indo-European Roots.