1. To function or operate at the exact same time and rate as something else. ("Sync," or less commonly "synch," is short for "synchronize.") I'm trying to get these lights to sync up so that they don't alternate when they blink. The audio and visuals of this video don't sync up quite right.

2. To cause two or more things to function or operate at the exact same time and rate. In this usage, a noun or pronoun can be used between "sync" and "up." We need to sync up the motors perfectly or the entire system will fail. Everyone sync your watches up so we know exactly how much time we have left on the mission.

3. To achieve parity of content with something else. If you sign in with the same account on both devices, they will sync up automatically while connected to the Internet. I have these files saved to the cloud, but they're not syncing up on my computer for some reason.

4. To cause two or more things to achieve parity of content. In this usage, a noun or pronoun can be used between "sync" and "up." Our digital could storage solution allows you to sync up all your pictures, files, contacts, and other data up across an unlimited number of devices for a low monthly fee. IT has already synced the computers up in the new office, so there's no need to transfer any data when we start on Monday.

5. To coordinate with someone else so that all parties have the same plan, information, schedule, etc. OK, let's get together this weekend with all our notes so we can sync up one last time before the trial on Monday. Be sure to sync up with Mary so you're both on the same page about your responsibilities.