Desperado in chess refers to a situation where a piece is threatened by an opponent's piece, but rather than moving away, it captures the opponent's piece before being captured itself. It's like being a cowboy in a Wild West movie who knows they're surrounded by bad guys, but they decide to go out in a blaze of glory and take out as many bad guys as possible before they go down.
Imagine you have a knight on the board, and your opponent has a rook that is attacking your knight. Instead of just moving your knight away and letting your opponent capture an undefended piece for free, you can use the desperado tactic. You move your knight to attack one of your opponent's pieces that is worth more than your knight. Your opponent has to either move that piece or capture your knight, but either way, your attacked knight is free to move to safety.
The desperado tactic is a clever way of sacrificing a lesser-valued piece in order to gain some strategic advantage on the board. It's like sacrificing a pawn to protect your king or queen, except in this case, you sacrifice a knight or bishop to get rid of a more valuable piece of your opponent's. It can be a risky move, but if executed well, it can turn the tide of the game in your favor.
So, when you hear the word "desperado" in the context of chess, just remember that it's all about sacrificing a piece to gain some tactical advantage and hopefully come out on top in the end.