father-in-law vs begetter

father-in-law and begetter both are nouns.

Word	Noun	Adjective	Verb	Adverb
father-in-law	Yes	No	No	No
begetter	Yes	No	No	No

As nouns, begetter is a hypernym of father-in-law; that is, begetter is a word with a broader meaning than father-in-law:

Other hypernyms of father-in-law include father, male parent, in-law, relative-in-law.

father-in-law (noun)	begetter (noun)
the father of your spouse	a male parent (also used as a term of address to your father)