/ Thesaurus / A Synonyms of ad libitum Find synonyms for: Adverb1. ad lib, ad libitum, spontaneously, impromptuusage: without advance preparation; "he spoke ad lib"WordNet 3.0 Copyright © 2006 by Princeton University. All rights reserved. Related Content Daily Word Quiz: chicory Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language