flaskyoudaoicibaDictYouDict[flask 词源字典]
flask: [14] English acquired flask via French flasque from medieval Latin flasca, a word of uncertain origin. It occurs widely in the Germanic languages (German has flasche, for instance, and Dutch vlesch, and the related word flasce existed in Old English, although it did not survive into Middle English), but it is not clear whether the medieval Latin word was borrowed from Germanic, or whether the Germanic languages originally got it from a Latin word (Latin vāsculum ‘small vessel’, a diminutive form of vās – whence English vascular, vase, and vessel – has been suggested as a source).

The sense ‘gunpowder container’, first recorded in the 16th century, may have been inspired by Italian fiasco (source of English fiasco), which came from a variant medieval Latin form flascō. This also produced English flagon [15].
=> fiasco, flagon[flask etymology, flask origin, 英语词源]
flask (n.)youdaoicibaDictYouDict
mid-14c., from Medieval Latin flasco "container, bottle," from Late Latin flasconem (nominative flasco) "bottle," which is of uncertain origin. A word common to Germanic and Romanic, but it is unclear whether the Latin or Germanic word is the original (or whether both might have got it from the Celts). Those who support a Germanic origin compare Old English flasce "flask, bottle" (which would have become modern English *flash), Old High German flaska, Middle Dutch flasce, German Flasche "bottle." If it is Germanic, the original sense might be "bottle plaited round, case bottle" (compare Old High German flechtan "to weave," Old English fleohtan "to braid, plait"), from Proto-Germanic base *fleh- (see flax).

Another theory traces the Late Latin word to a metathesis of Latin vasculum. "The assumption that the word is of Teut[onic] origin is chronologically legitimate, and presents no difficulty exc[ept] the absence of any satisfactory etymology" [OED]. The similar words in Finnish and Slavic are held to be from Germanic.