Other forms: bigamies
When you are married to two people at the same time, that’s called bigamy. For example, if someone gets remarried before his or her previous marriage's divorce is finalized, that's bigamy.
The noun bigamy originates in the Greek as a combination of the prefix bi-, meaning “double,” and gamos, which means “marrying.” There are some cultures and religions that promote, encourage and otherwise allow polygamy, but where it’s illegal, which is most of the Western Hemisphere, it’s called bigamy.