What is a plain cap or headdress for women or girls; especially, one tying under the chin by a very broad band, generally of the same material as the cap itself. Thackeray called?

mobcap — A plain cap or headdress for women or girls; especially, one tying under the chin by a very broad band, generally of the same material as the cap itself. Thackeray. (Webster's 1913.)