Definition of "in sync"

in sync

prepositional phrase
1. Used other than figuratively or idiomatically: see in,‎ sync.
2. Working well together; agreeing with each other.
  Quotations
  We / Used to be / Just like twins / So in sync
  2008, Katy Perry, Dr. Luke, Max Martin, “Hot n Cold”, in One of the Boys‎, performed by Katy Perry