'A gaberlunzie is a license to beg, Sassenach,' Jamie explained. 'It's good within the borders of the parish, and only on the one day a week when begging's allowed. Each parish has its own, so the beggars from one parish canna take overmuch advantage of the charity of the next.'" —Diana Gabaldon, Outlander (NY: Delacorte Press, 1991), 325–326
A beggar. A good Scots word this, of the medieval period, though sadly nobody has much idea where it comes from. The first part looks as though it might have something to do with gaberdine, originally a garment worn by a pilgrim. This may well be, because another name for a gaberlunzie in medieval times was bluegown. Taken from the colour of his dress, this was the name in medieval Scotland for a person who was a king's licensed beggar or beadsman, a person who was paid to pray for the souls of others by telling his beads. (Beadsman comes from the original meaning of bead, a prayer; it was only later that it took on its modern sense through association with the rosary.)
You will find it many times in Scots literature, especially in the old ballad The Gaberlunzie Man and in James Ballantine's story The Gaberlunzie's Wallet. But if it's Scots we're after, we had best turn to Sir Walter Scott. He doesn't fail, and here it is in Redgauntlet: ìBetter say naething about the laird, my man, and tell me instead, what sort of a chap ye are that are sae ready to cleik in with an auld gaberlunzie fiddler?î (Cleik, a version of cleek, from a noun meaning a hook, so to link oneself with somebody.) It's also in several other of Scott's books, so he probably must be given the credit of having popularised it to readers outside Scotland.