Synodic is a 7 letter English word. It's valid Scrabble word worth 13 points. It's valid Words with friends word worth 14 points.
You can make 158 anagrams from letters in synodic (cdinosy).
1555-65; Late Latin synodicus Greek synodikós. See synod, -ic
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.
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.