The term 'SMALL CASK' can be solved by the three-letter word 'KEG'. A KEG is a small barrel or cask, usually made of aluminum or stainless steel, that is used to store and transport beer. It is also commonly used to store other beverages such as wine, cider, and kombucha. Kegs are often used in bars and restaurants, as well as for home brewing. They are typically filled with pressurized gas, which helps to keep the contents fresh and carbonated.