IPA: /ˌɛn.təˈteɪ.nɪŋ.li/
KK: /ˌɛntərˈteɪnɪŋli/
In a way that is enjoyable and holds attention.
The comedian told stories entertainingly, making everyone laugh.
Entertainingly → It is formed from "entertain" (from Old French *entretenir*, meaning to hold among or support) and the suffix "-ingly" (meaning in a manner of). The word "entertainingly" means in a manner that holds attention or provides amusement.
Think of the word 'entertain' as holding someone's attention, and the '-ingly' shows how it's done — so entertainingly means doing something in a way that keeps people amused.