Where does “jan” come from?

Jan comes from Arabic جِنّ, a word for supernatural beings or spirits in Islamic tradition.

jan (English): Obsolete form of jinn

Definitions

Step	Language	Word	Meaning
1	English	Janet	—
2	English	Jane	A woman, often specifically a girlfriend;...
3	French	Jeanne	Jane, feminine of John
4	Old French	Jehane	—
5	Medieval Latin	Johanna	—
6	Latin	Joanna	—
7	Ancient Greek	Ἰωάννα	—
8	Hebrew	יוֹחָנָה	—
9	Hebrew	יוֹחָנָן	God is gracious
10	Hebrew	יְהוֹחָנָן	God is gracious

jan — Etymology, Origin & Word History | Etymology Explorer