IPA: /ˌoʊvərˈwɛlm/
KK: /oʊvərˈwɛlm/
To have a strong effect on someone emotionally or mentally, or to defeat someone completely. It can also mean to give someone too much of something or to cover something completely with a large amount of something.
The news of her promotion overwhelmed her with joy.
Past: overwhelmed
Past Participle: overwhelmed
Overwhelm is formed from "over-" (meaning excessively or beyond) and "whelm" (from Old English "hwelfan", meaning to turn over or cover). The word describes the act of being covered or submerged excessively, often by emotions or tasks.
Think of being 'covered excessively' ('over-') by something overwhelming, like emotions or responsibilities.