IPA: //ʌnˈspɛrɪŋli//
KK: /ʌnˈspɛrɪŋli/
In a way that does not hold back or show mercy; without restraint or limitation.
She criticized the project unsparingly, pointing out every flaw and mistake.
Unsparingly → It is formed from "un-" (meaning not) and "sparing" (from the verb "spare", meaning to hold back or be frugal). The word "unsparingly" means not holding back or being generous without restraint.
Think of 'not' holding back ('un-') and being 'frugal' ('sparing') — that's why unsparingly means to give freely without restraint.