Bigamy is the offence of marrying one person while still legally married to another — the deception and the illegality are central to it. Polygamy is the broader term for having more than one spouse, describing a marriage practice rather than a crime, and it is lawful in some jurisdictions.
The core difference
One names a criminal offence; the other names a marriage system.
- bigamy — entering a marriage while an existing one is legally in force. A criminal offence in most jurisdictions.
- polygamy — having multiple spouses. Lawful in some jurisdictions, and the subject of anthropological description rather than criminal law.
The sub-terms
Polygyny is one man with multiple wives; polyandry is one woman with multiple husbands. Polygamy covers both, though it is often used loosely as though it meant only the first.
The words
All are built from Greek gamos, marriage: bi- two, poly- many, mono- one. Monogamy completes the set.
Frequently asked questions
Is polygamy illegal?
It depends entirely on the jurisdiction. It is lawful in some countries and prohibited in others; bigamy is a criminal offence in most.
What is the difference between polygyny and polyandry?
Polygyny is one man with several wives; polyandry is one woman with several husbands. Polygamy covers both.
What is the root of these words?
Greek gamos, marriage, with prefixes bi- (two), poly- (many) and mono- (one).