Dictionary.com
Thesaurus.com

whosoever

American  
[hoo-soh-ev-er] / ˌhu soʊˈɛv ər /

pronoun

possessive

whosesoever,

objective

whomsoever

  1. whoever; whatever person.

    Whosoever wants to apply should write to the bureau.
whosoever British  
/ ˌhuːsəʊˈɛvə /

pronoun

  1. an archaic or formal word for whoever

"Collins English Dictionary — Complete & Unabridged" 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Etymology

Origin of whosoever

Middle English word dating back to 1175–1225; whoso, ever

Definitions and idiom definitions from Dictionary.com Unabridged, based on the Random House Unabridged Dictionary, © Random House, Inc. 2023

Idioms from The American Heritage® Idioms Dictionary copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.