A vacuum flask is an insulating storage vessel that greatly lengthens the time over which its contents remain hotter or cooler than the flask's surroundings.
DANGEROUS GLASS VACUUM THERMOS FLASK, DO NOT USE by LIFE107, FAMILY, FITNESS, BOXING, TRAVEL & HEALTH
Invented by Sir James Dewar in 1892, the vacuum flask consists of two flasks, placed one within the other and joined at the neck.
The Legendary Stanley Classic Vacuum Flask by Stafford Outdoor Leisure
The gap between the two flasks is partially evacuated of air, creating a near-vacuum which significantly reduces heat transfer by conduction or convection.
Convection is the heat transfer due to the bulk movement of molecules within fluids such as gases and liquids, including molten rock.
Vacuum flasks are used domestically, to keep beverages hot or cold for extended periods of time, and for many purposes in industry.
A drink is a liquid intended for human consumption.