Definition of "extemporize" [ex•tem•po•rize]

• To do or perform (something) without prior preparation or practice: extemporized an acceptance speech. (verb-transitive)
• To perform an act or utter something in an impromptu manner; improvise: "bravely demonstrating his ability to extemporize intelligently” ( William Safire). (verb-intransitive)

American Heritage(R) Dictionary of the English Language, Fifth Edition. Copyright (c) 2011 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.

• "You really have to know the melody inside out and that allows you to embellish, to extemporize on it with freedom."
• "I'm discovering that I like Danilaw a lot -- he's got the ability to extemporize political speeches like a trained skald and he's also pretty funny."
• "He did not care to ascertain if she had replenished the lilacs in the tower room, and, at lunch, which was shared with three farm college students from Davis, he found himself forced to extemporize a busy afternoon for himself when Paula tentatively suggested that she would drive Graham up from Eldorado."