syn·od·ic
| \ sə-ˈnä-dik
\
variants:
or synodical \ sə-ˈnä-di-kəl
\
2
usually synodic
[ Greek synodikos, from synodos meeting, conjunction ]
: relating to conjunction
especially
: relating to the period between two successive conjunctions of the same celestial bodies (such as the moon and the sun)