A cinch is something extremely easy to do, so simple that you can accomplish it without much effort or worry. If your teacher asks what 2 plus 2 equals, answering is a cinch. When you've practiced your violin piece a hundred times, performing it becomes a cinch.

The word originally comes from horseback riding, where a cinch is the strap that holds a saddle firmly on a horse's back. Cowboys would pull the cinch tight to make sure the saddle was secure, literally cinching it down. When something is cinched, it's fastened tightly and securely. You might cinch your backpack straps to keep it snug against your back.

From this idea of securing something firmly came the modern meaning: when you cinch a victory, you make it certain. If your basketball team is ahead by 30 points with one minute left, you've cinched the win.

People also use cinch to mean an absolute certainty: “It's a cinch that summer vacation will arrive eventually.” When something is described as a cinch, it means you can relax because success is practically guaranteed.