dewar

This term is a specialized piece of laboratory equipment, primarily used in physics, chemistry, and cryogenics. It is named after Sir James Dewar, who invented the vacuum flask. While a common household thermos is technically a type of Dewar vessel, in a professional scientific context, a "dewar" typically refers to larger, industrial-grade containers designed for the bulk storage and transport of cryogenic fluids.

Because it describes a specific physical object, it follows standard English countability rules. It is used in technical registers and is rarely encountered in general conversation unless discussing laboratory procedures or extreme temperature experiments.