If you are a werewolf, your animal transformation is synchronous with the lunar cycle. When something is synchronous, it occurs in time or at the same time with something else.
In synchronous, you see syn- meaning "together," and -chron- meaning "time." If things such as swimming moves are synchronous, they are said to be in sync. Jewel thieves and undercover operatives synchronize their watches so that the team ensures synchronous actions. If the police question you about a crime and your alibi is that you were out dancing, it means that the occurrences of the crime and your dance were synchronous, so you could not be the perpetrator.