Rig means to set something up in a dishonest way so that you get the result you want. When someone rigs a game, they arrange things secretly so they'll win no matter what. If a contest is rigged, the winner was chosen ahead of time, making everyone else's efforts meaningless. Politicians sometimes accuse each other of trying to rig elections, and if you shuffle a deck of cards in a special way to give yourself good hands, you're rigging the game.

The word suggests sneaky preparation rather than obvious cheating. A rigged system looks fair on the surface but has hidden tricks built in. A carnival game might be rigged so it's nearly impossible to win the big prize, even though it looks easy.

The word has a completely different meaning in sailing and construction. Ships have rigging, the system of ropes and cables that supports the masts and controls the sails. Oil companies drill with massive offshore structures called oil rigs. To rig something in this sense means to set it up properly and carefully, like when sailors rig their boat before a voyage by checking all the ropes and equipment. Here, rigging means honest, skillful preparation, the opposite of the cheating meaning.