/ flɑːsk; NAmE flæsk/ noun
1.
a bottle with a narrow top, used in scientific work for mixing or storing chemicals
2.
( BrE ) = vacuum flask :
a flask of tea / coffee
—compare Thermos
3.
( especially NAmE ) = hip flask
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WORD ORIGIN
Middle English (in the sense cask ): from medieval Latin flasca . From the mid 16th cent. the word denoted a case of horn, leather, or metal for carrying gunpowder. The sense glass container (late 17th cent.) was influenced by Italian fiasco , from medieval Latin flasco . Compare with flagon .