Wiktionary
a. Mutually synchronized
Usage examples of "in phase".
If another ship could match relativistic velocity to within fifteen or twenty percent, his wormhole space and yours were in phase.
At that time we didn't realize that the nova explosion was merely a destructive application of the principle used in phase-shift drive.
That assumes that the ships can communicate with each other even when they're not in phase with us.
Except there wasn't anything to feel, it's just sort of neutral in phase, and I had to walk the bicycle right along.
Other transmitters either jam the first or dampen it by reversing the amplitude in phase.
This will mean that the waves from the slits will not be in phase with each other when they arrive at the screen: in some places the waves will cancel each other out, and in others they will reinforce each other.
In this imagery, the features of a system are structures in phase space that give it a well-defined 'geography'.
Since this peak was smooth and flat, a group of nearly straight paths clustered around it all had similar phase shifts, and these paths allowed many more components to arrive in phase with each other, reinforcing each other, than any equivalent group on the slopes.