IPA: //ˈfeɪlɪŋli//
KK: /ˈfeɪlɪŋli/
In a way that shows failure or inadequacy.
He tried failingly to convince her to stay.
Failingly → It is formed from "fail" (from Old French *faillir*, meaning to be lacking or to fall short) and "-ingly" (a suffix used to form adverbs indicating manner). The word "failingly" means in a manner that is lacking or falling short.
Think of the word 'fail' which means to fall short, and remember that 'failingly' describes doing something in a way that lacks success.