IPA: /ˈnæstɪli/
KK: /ˈnæs.tɪ.li/
In a way that is unpleasant, mean, or offensive.
She spoke nastily to her friend after the argument.
Nastily → It is formed from "nasty" (originating from the Middle English *nasti*, meaning unpleasant or offensive) and the suffix "-ly" (meaning in a manner of). The word "nastily" means in a manner that is unpleasant or offensive.
Think of the word 'nasty' to remember that 'nastily' means doing something in an unpleasant or offensive way.