To sync (short for synchronize) means to make things happen at the same time or work together in a coordinated way. When you sync your tablet with your computer, you're making sure they both have the same files, photos, and information. When dancers move in sync, their movements match perfectly, like mirror images.

The word comes from technology but works in many situations. A band playing in sync means every musician follows the same rhythm and tempo. If you and your best friend show up wearing similar outfits without planning it, you might joke that you're in sync. When a movie's audio gets out of sync with the video, the actors' lips move at different times from their voices, which feels weird and wrong.

In swimming, synchronized swimming is a sport where athletes perform elaborate routines while staying perfectly coordinated with each other and the music. The goal is to move as one.

You'll also hear people talk about being in sync with someone when they understand each other well or think alike. If you and a teammate are in sync during a game, you anticipate each other's moves and work together smoothly without needing to discuss every play.