Etymology: [ flask, fl[a]sk ] (noun.) 1549. From Middle English flask (“cask, keg”), from flaske (“case”), from Anglo-Norman flaske (subject case), flascon (object case), from Late Latin flascō ‘bottle’, from Frankish *flasko (cf. Dutch (Flemish) vlesch), from Proto-Germanic *flaskōn ‘braid-covered bottle, wicker-enclosed jug’ (cf. Old English flaxe, flasce, West Frisian flesse, German Flasche), from Proto-Indo-European *plok̑-skō (cf. Lithuanian plókščias (“flat”), Old Church Slavonic ploskŭ (“flat”)).
Sense 2 from Italian fiasco and sense 3 from Middle French flasque (“powder flask”), itself from Old Spanish flasco, frasco, all words being of the same origin as above.
Synonyms: alembic, ampulla, bag, beaker, bottle, canteen, carafe, caster, chalice, crock, cruet, crystal, decanter, demijohn, ewer, fiasco, flacon, flagon, flasket, glass