Examples from the Web for synodic
Why, because twenty-seven days is about the synodic period of solar rotation.
Lunar Year, a period of 12 synodic lunar months, being about 354.5 days.The Nuttall Encyclopaedia|Edited by Rev. James Wood
They determined correctly within a small fraction the length of the synodic revolution of the moon.
The correlation with the synodic rotation of the Sun was practically perfect.