king

/kɪŋ/ noun [C]

Definition

› a person, company, or organization that is thought to be the best or most successful: It is widely considered to be king of the supermarket chains.

sb/sth is king › used to say that someone or something is the most important part of something or has the most influence: In mergers and acquisitions, cash is king. They all followed the principle that the customer is king. Media executives are fond of saying that content is king.

(Definition of king noun from the Cambridge Business English Dictionary © Cambridge University Press)