IPA: /ˈdɜːrtɪli/
KK: /ˈdɜːrtɪli/
In a way that is not clean or is covered with dirt.
The children played dirtily in the mud after the rain.
Dirtily is formed from "dirt" (from Old English "dyrt", meaning soil or filth) and "-ily" (a suffix forming adverbs meaning in a manner of). The word "dirtily" means in a manner that is dirty or unclean.
Think of 'dirt' as something unclean, and the '-ily' shows how something is done. So, when you think of dirtily, imagine doing something in a dirty way.