A shingle is a thin piece of wood used in making a roof or a signboard outside an office, especially a doctor’s or lawyer's. If you’re opening a business, hang your shingle outside so people can find you.
One kind of shingle is a rectangular piece of wood or other material used to make a roof. The other is a type of small sign outside an office that shows someone is ready to see clients, patients, or other types of customers. The word shingle is from the Latin scindere for "to split,” as in splitting wood, and whatever you do with a shingle, it’s a small flat hunk of wood.