Syzygy is a term that pertains to the alignment of celestial bodies, particularly the sun, moon, and earth. It is a rare and unique occurrence, and as such, there are only a few synonyms for the word. One possible synonym is "conjunction," which refers to the alignment or joining of two or more celestial bodies. Another synonym is "alignment," which pertains to the same idea of bringing things into a straight and orderly arrangement, as seen in the alignment of the planets. Other possible synonyms include "intersection," "coincidence," and "overlap," all of which describe the occurrence of things coming together or crossing paths in some way.