extemporaneity
noun
ex·tem·po·ra·ne·i·ty (ˌ)ek-ˌstem-pə-rə-ˈnē-ə-tē 
-ˈnā-
: the quality or state of being extemporaneous
Example Sentences
Recent Examples on the Web Is there any inherent contradiction between being the king of extemporaneity, musically, and then also the king of designing things within a seemingly meticulous, if visually enrapturing, inch of their life? 
Chris Willman, Variety, 17 July 2022
Chris Willman, Variety, 17 July 2022 Word History
First Known Use
1937, in the meaning defined above