IPA: //huːˈsoʊˌɛvər//
KK: /hwuˈsoʊˌɛvər/
A word used to refer to any person or people, without specifying who they are.
Whosoever believes in the power of kindness will find happiness.
Whosoever is formed from "who" (from Old English "hwa", meaning a person) and "soever" (an archaic form of "soever", meaning whichever or whatever). The word "whosoever" means any person who or whichever person.
Think of 'who' as referring to a person and 'soever' as meaning whichever — together, they help you remember that whosoever refers to any person.