Where does “家内” come from?

家内 (Japanese) comes from Japanese 家, from Japanese 家紋, from Middle Chinese かもん.

家内 (Japanese): wife; family; the inside of the house

Definitions

家内 traces back through two separate lines of ancestry.

Step	Language	Word	Meaning
1	Japanese	家	a house; one's own home; a home, household
2	Japanese	家紋	a crest for a household or family
3	Middle Chinese	かもん	—

Step	Language	Word	Meaning
1	Japanese	内	inside, within; between, among; while, during,...
2	Middle Chinese	內	—