IPA: /ˌoʊvərˈwɛlmɪŋli/
KK: /oʊvərˈwɛlmɪŋli/
In a way that is very strong or intense, often making it difficult to handle or deal with.
The support for the new policy was overwhelmingly positive.
Overwhelmingly → It is formed from "over-" (meaning excessively or beyond) and "whelm" (from Old English "hwelfan", meaning to turn over or cover). The suffix "-ing" indicates the action or process, and "-ly" (meaning in a manner). Thus, "overwhelmingly" describes something that is excessively covering or overpowering in manner.
Think of something that is 'excessively' ('over-') 'covering' or 'turning over' ('whelm') — that's why overwhelming means it has a strong, overpowering effect.
No commonly confused words.