A wallet is a small, flat case that can be used to carry such personal items as cash, credit cards, and identification documents (driver’s license, identification card, club card, etc.), photographs, transit pass, gift cards, business cards and other paper or laminated cards.
The word “wallet” has been in use since the late 14th century to refer to a bag or a knapsack for carrying articles (see for example knapzak in Dutch and Frisian), indeed its early usage by Shakespeare described something that we would recognise as more like a backpack today. The word may derive from Proto-Germanic. The ancient Greek word kibisis, said to describe the sack carried by the god Hermes and the sack in which the mythical hero Perseus carried the severed head of the monster Medusa, has been typically translated as “wallet”. Usage of the term “wallet” in its modern meaning of “flat case for carrying paper currency” in American English dates to 1834 but this meaning was one of many in the 19th century and early 20th century.