gamo-, gam-, -gamy, -gamous +

(Greek: marriage, union; wedding; pertaining to sexual union)

pentagamous
A reference to being married to five spouses at the same time.
polyandrist
1. The marriage of a woman to several (more than two) men at the same time.
2. A woman who practices, or favors, polyandry.
polygamist
Someone who commits polygamy or who has multiple marriages.
polygamous
1. A reference to the civil offense of having several wives or husbands at the same time; or having more than two wives or husbands at the same time.
2. Bigamy literally means a second marriage distinguished from a third or additional marriage; while polygamous refers to many marriages and implies more than two.
A man with his polygamous wives.
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To marry once is a duty, twice a folly, thrice is madness.
—Dutch Proverb
God help the man who won't marry until he finds a perfect woman, and God help him even more if he finds her.
—Benjamin Tillett

Regardless of how they are expressed, all of them represent excesses!

With polygyny and polygynous, we have the marriage of a man to more than two women at the same time. Then we have polygamy and polygamous:

  1. The civil offense of having several wives or husbands at the same time; or having more than two wives or husbands at the same time.
  2. Bigamy literally means a second marriage distinguished from a third or additional marriage; while polygamy means many marriages and implies more than two.

Polygamia est plurium simul virorum uxorumve conubium.

"Polygamy is the marriage with many husbands or wives at one time".

Pointing to a page about polygamy. There are more details about polygamy here.

polygynous
A reference to the marriage of a man to more than two women at the same time.
pseudogamy, pseudogamous
A false marriage.
quadrigamist
Someone who has married four times and as a result, has four spouses; such as, four wives or four husbands at the same time.
quadrigamy
Married to four spouses at the same time or a fourth marriage.
syngamy, sygamous, syngamic
1. Free interbreeding between organisms.
2. The fusion of two cells, or of their nuclei, in reproduction.
tetragamy, tetragamous
1. A fourth marriage.
2. Marriage with four spouses simultaneously.
trigamous
1. The state of having three wives or husbands at the same time.
2. The crime of contracting a third marriage while two previous spouses are alive.
3. Marriage for the third time after the death of former wives or husbands.
xenogamy, xenogamous
In botany, fertilization by pollen from another plant of the same species; cross-fertilization.
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