Definitions

1. pronoun

used to refer to a person or people whose identity is unknown or irrelevant

“The person who submitted the application will be contacted by whoever/whosever is responsible for the project.”

2. noun

a person or people whose identity is unknown or irrelevant

“The new employee is a whosever, and the manager is trying to figure out their background.”

3. pronoun

used to refer to a person or people whose identity is unknown or irrelevant, especially in formal or literary contexts

“Whosever may be able to provide the necessary information will be contacted by the authorities.”