verb [no object] Compose or perform something such as music or a speech without preparation; improvise: he extemporized at the piano [with object]: she was extemporizing touching melodiesSynonymsimprovise, ad lib, play it by ear, think on one's feet, throw/cobble something together, make it up as one goes along, take it as it comes informal busk it, wing it, do something off the cuff, do something