A stratagem is a clever plan or trick designed to outwit an opponent or solve a tricky problem. The word suggests something more cunning than a simple plan: a stratagem involves creative thinking to gain an advantage, often by surprise or misdirection.

In ancient warfare, generals used stratagems constantly. A famous example is the Trojan Horse: Greek soldiers hid inside a giant wooden horse that the Trojans brought into their city, thinking it was a gift. That night, the hidden soldiers emerged and opened the city gates. That's a classic stratagem: achieving victory through cleverness rather than direct force.

You might use a stratagem in everyday life too. If your little brother always grabs the best cookie from the jar, you might use the stratagem of hiding one good cookie in the back before he gets there. If you're playing chess and you sacrifice a small piece to trap your opponent's queen, that's a stratagem.

Today, we use the word for any clever, somewhat sneaky plan, whether on the battlefield, the chessboard, or in everyday problem-solving. A stratagem works because you've thought several steps ahead and anticipated what others will do.