IPA: /ˈlæf.ɪŋ.li/
KK: /ˈlæfɪŋli/
In a way that shows laughter or amusement, often used to indicate that something is funny or not taken seriously.
She laughed at the joke laughingly, enjoying every moment of the humor.
Laughingly → It is formed from "laugh" (from Old English "hlæhhan", meaning to express joy or amusement) and "-ingly" (a suffix used to form adverbs indicating manner). The word "laughingly" means in a manner that expresses joy or amusement.
Think of expressing joy or amusement ('laugh') in a certain way ('-ingly') — that's why laughingly means doing something in a joyful or amused manner.