▪ a narrow-necked glass container, typically conical or spherical, used in a laboratory to hold reagents or samples.
▪ a narrow-necked bulbous glass container, typically with a covering of wickerwork, for storing wine or oil.
▪ a vacuum flask.British
▪ a hip flask.
▪ the contents of a flask: "a flask of coffee"
2. an extremely strong lead-lined container for transporting or storing radioactive nuclear waste.
3. short for powder flaskhistorical
Word OriginMiddle English (in the sense ‘cask’): from medieval Latin flasca. From the mid 16th century the word denoted a case of horn, leather, or metal for carrying gunpowder. The sense ‘glass container’ (late 17th century) was influenced by Italian fiasco, from medieval Latin flasco. Compare with flagon.