IPA: //wɒtˈsoʊˌɛvər//
KK: /wɑtˈsoʊˌɛvər/
Used to emphasize a lack of limitation or restriction; it means 'at all' or 'in any way'.
I have no interest whatsoever in that movie.
Used to emphasize a lack of restriction or limitation; anything at all.
You can choose whatsoever you like from the menu.
Whatsoever → It is formed from "what" (from Old English "hwæt", meaning what or which) and "soever" (from Old English "swa" meaning so or in this way, combined with "ever" meaning at any time). The word "whatsoever" means anything at all or in any way, emphasizing the totality of the subject in question.
Think of 'what' as asking about anything and 'soever' as meaning in any way — together, they help you remember that 'whatsoever' refers to anything at all.