IPA: /nɪˈɡlɛktfəli/
KK: /nɪˈɡlɛktfəli/
In a way that shows a lack of care or attention.
She neglected her duties neglectfully, leading to many mistakes.
Neglectfully → It is formed from "neglect" (from Latin "neglegere", meaning to disregard or not choose) and "-fully" (meaning in a manner full of). The word "neglectfully" means in a manner that shows disregard or lack of attention.
Think of 'neglect' as meaning to 'disregard' something, and '-fully' indicates the manner in which it is done. So, neglectfully means doing something in a way that shows disregard.