jan1, jaun verb
1 to know: Dinnae ye jan that the lassie didnae mean tae insult ye? [Don’t you know that the girl did not mean to insult you.] 20-.
2 to discover 19. Compare jau etymology: origin obscure; possibly a development from Romany jin ‘to know’; also collected by EMcC/PS; also attested by Galloway Tinkler-Gypsies, JS, BS in TDITA, SS and DW in DB; form jaun sense 2 attested by Grose as Scotch Cant note:

Grellmann (1787) collected the form Me tʃchana ‘To know.’ from Continental gipsies. Smart & Crofton (1875) collected the form Jin sense 1 with the same meaning from English Gypsies.

Smart & Crofton (1875) collected the form Jin v., ‘to know’ from English Gypsies.

Sense 1 also attested by Canadian Paul Pope (2013).