Polygyny is a form of polygamy entailing the marriage of a man to several women. The term polygyny is from Neoclassical Greek πολυγυνία (polugunía); from Ancient Greek πολύ (polú) 'many', and γυνή (gunḗ) 'woman, wife'.

Polygamy is the practice of marrying multiple spouses. When a man is married to more than one wife at the same time, it is called polygyny. When a woman is married to more than one husband at the same time, it is called polyandry. In sociobiology and zoology, researchers use polygamy in a broad sense to mean any form of multiple mating.