The Wazir
The Wazir is a piece from ancient Chess variants, and moves one square Rookwise.From e4, a Wazir can reach e5, f4, e3, or d4; a Wazir can reach every square on the board, but takes a while to get there.
By itself, the Wazir is too weak a piece to be of much interest, but its power can be combined with the powers of other pieces to make new and interesting ones. By itself, it is worth little more than a Pawn, but in combination with other pieces it is worth half a Knight, more or less.
The funny notation for this is simply the letter W, because the Wazir is one of the basic geometric ingredients used in the recipes for other pieces.
The funny notation could also be W1, meaning that it is a one-step orthogonal mover. Please notice that W7 (on an 8x8 board) is the Rook; the Rook is nothing but an extension of the basic geometrical move of the W.
The Pawnless endgame with King and three Wazir versus King is winnable, but not easy. Two Wazirs (and the King) can confine the enemy K to a corner and stalemate, but it isn't easy.