Where does “紋” come from?

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

紋 (Japanese): Synonym of 家紋

Definitions

Step	Language	Word	Meaning
1	Japanese	家紋	a crest for a household or family
2	Middle Chinese	かもん	—

紋 — Etymology, Origin & Word History | Etymology Explorer