IPA: /ˈhændsəmli/
KK: /ˈhændsəmli/
In a way that is attractive or pleasing; often used to describe something done in a generous or impressive manner.
He was rewarded handsomely for his hard work on the project.
Handsomeness is derived from "handsome" (from Middle English *handsome*, meaning easy to handle or pleasing) and the suffix "-ly" (meaning in a manner of). The word "handsomely" means in a manner that is pleasing or attractive.
Think of 'handsome' as something that is pleasing or attractive, and remember that 'handsomely' means doing something in a pleasing manner.