polygamy vs wedlock

polygamy and wedlock both are nouns.

Word	Noun	Adjective	Verb	Adverb
polygamy	Yes	No	No	No
wedlock	Yes	No	No	No

As nouns, wedlock is a hypernym of polygamy; that is, wedlock is a word with a broader meaning than polygamy:

polygamy: the condition or practice of having more than one spouse at a time
wedlock: the state of being a married couple voluntarily joined for life (or until divorce)

Other hypernyms of polygamy include marriage, matrimony, spousal relationship, union.

polygamy (noun)	wedlock (noun)
the condition or practice of having more than one spouse at a time	the state of being a married couple voluntarily joined for life (or until divorce)