A large cask or barrel, especially one holding about 252 imperial gallons (approximately 954 litres) of beer or wine. The cooper finished repairing the oak tun used for aging the ale.
A unit of liquid capacity, chiefly for wine or beer, equal to 252 imperial gallons (about 954 litres). The contract specified that two tuns of wine would be delivered every quarter.
Biology: the dormant, dehydrated state assumed by some tardigrades and other micro-animals to survive extreme conditions. When desiccated, the tardigrade curls into a tun and can remain viable for years.