IPA: /ɪmˈprɒvɪzətəri/
KK: /ɪmˈprɑːvɪzəˌtɔːri/
Something that is created or performed without planning or preparation, often in a spontaneous manner.
The actor's improvisatory skills impressed the audience during the live performance.
Improvisatory → It is formed from "improvisus" (from Latin, meaning unforeseen or unprepared) and the suffix "-ory" (meaning relating to or characterized by). The word "improvisatory" refers to something that is characterized by being made or done without preparation.
Think of something that is 'unforeseen' or 'not prepared' — that's what improvisatory means, relating to creating on the spot.