king

1. (countable or uncountable) Something that has a preeminent position.Examples: "In times of financial panic, cash is king."; "It would be difficult, for example, to imagine a bigger, more obvious subject for comedy than the laughable self-delusion of washed-up celebrities, especially if the washed-up celebrity in question is Adam West, a camp icon who can go toe to toe with William Shatner as the king of winking self-parody."countableuncountable

2. A component of certain games.Examples: "The objective of each player is to place the opponent’s king ‘under attack’ in such a way that the opponent has no legal move. […] If the arbiter observes both kings are in check, or a pawn stands on the rank furthest from its starting position, he/she shall wait until the next move is completed."

3. A component of certain games.

4. (UK, slang) A king skin.Examples: "Oi mate, have you got kings?"UKslang

5. (graph theory) A vertex in a directed graph which can reach every other vertex via a path with a length of at most 2.