IPA: /ʌnˈɛndɪŋli/
KK: /ʌnˈɛndɪŋli/
In a way that has no end or limit; continuously or forever.
The rain fell unendingly, soaking the ground and filling the rivers.
Unendingly → It is formed from "un-" (meaning not) and "ending" (from the root "end" which comes from Old English "endian", meaning to come to a conclusion) and the suffix "-ly" (meaning in a manner). The word "unendingly" means in a manner that is not coming to a conclusion or without end.
Think of 'not' ('un-') and 'coming to a conclusion' ('end') to remember that 'unendingly' describes something that goes on without stopping.