The word QUEEN has two definitions in chess. Let’s look at both.
QUEEN (def. 1) (+S) [n. A piece combining the moves of the rook and bishop, making the strongest piece at the beginning of the game.]
QUEEN (def. 2) (+ED, +ING, +S) [v. To promote a pawn to a queen]
OK, fine.
But what if someone wanted to promote to a Bishop, Rook, or Knight? You can’t Bishop a pawn. And Rooking a pawn doesn’t make sense either.
Now, it is possible you could Knight a Pawn, but only if the man’s name is Mr. Pawn and he does something really very good for the British Empire. But since we are only talking about chess, this doesn’t make sense after all.
Interesting is the fact is that you can King a piece in checkers (or “draughts.”). But you can’t Queen a piece in checkers or in chess (only pawns).
The umbrella term for promoting a pawn to Knight, Bishop, or Rook, is “underpromotion”. Which, at first, sounds like a demotion. But all it means is the piece the pawn is being promoted to is not the strongest piece possible, even if the underpromoted piece actually wins the game (as promoting to a queen can sometimes lead to an immediate stalemate).
By the way, the word PROMOTE is defined as [v. To upgrade a pawn, upon reaching the eighth rank, to a Rook, Knight, Bishop, or Queen, of one’s own color.]
You can’t promote your pawn to a piece of the opposite color, even if it will benefit you (and yes, this can happen).]
Confused? Good! Just wait until we start talking about OPPOSITION and ZUGZWANG.
The Gambit Chess Player 