IPA: /ˈhɑːrtɪli/
KK: /ˈhɑrtɪli/
In a warm and sincere way; with enthusiasm or enjoyment.
They laughed heartily at the joke.
Heartily → It is formed from "heart" (from Old English "heorte", meaning the organ that pumps blood and also symbolizes emotion) and the suffix "-ly" (meaning in a manner of). The word "heartily" means in a manner that expresses warmth or sincerity, as if from the heart.
Think of the word 'heart' representing warmth and emotion, and remember that 'heartily' means doing something with genuine feeling.