IPA: /ˈtʃɪə.rɪ.li/
KK: /ˈtʃɪrɪli/
In a way that shows happiness and positivity.
She greeted everyone cheerily as she entered the room.
Cheerily → It is formed from "cheer" (from Old French *chiere*, meaning face or countenance, which evolved to mean a state of happiness or joy) and "-ily" (a suffix used to form adverbs). The word "cheerily" means in a joyful or happy manner.
Think of someone showing a happy 'face' ('cheer') and doing so in a lively way ('-ily'). This helps you remember that 'cheerily' means to act in a joyful manner.