What does flask mean?
A flask is a container designed for holding liquids, distinguished most characteristically by its narrow neck, which limits spills and evaporation while allowing easy pouring. The word spans several familiar objects: the glassware of the chemistry laboratory, where Erlenmeyer and round-bottomed flasks are standard equipment; the small, flat metal hip flask tucked into a pocket for carrying spirits; and the insulated vacuum flask that keeps coffee hot on a long hike or soup warm on a winter outing. Because each of these senses involves sealing or carefully controlling a liquid, the word carries connotations of portability, self-sufficiency, and careful handling. Flask works equally well in technical writing and casual conversation, making it a versatile and practical term. Its history adds a twist: it descends ultimately from a Germanic source carried into Medieval Latin as 'flasco', a lineage it shares, surprisingly, with the Italian 'fiasco', which originally named the straw-wrapped wine bottle before coming to mean a humiliating failure.
nounA flask is a container, typically made of glass or metal, with a narrow neck, used for holding liquids — ranging from laboratory vessels to small pocket bottles for carrying spirits. The term also covers insulated containers designed to keep their contents hot or cold.
- A vessel with a narrow neck for holding liquids, especially in laboratory use (e.g. an Erlenmeyer or round-bottomed flask).
- A small flattened bottle, often pocket-sized, used for carrying spirits (a hip flask).
- An insulated container that keeps liquids hot or cold, such as a vacuum flask.
"The chemist swirled the pale blue solution inside the Erlenmeyer flask before heating it over the flame."
"She unscrewed her hip flask and offered him a sip of whisky against the cold."
"Bubbles rose steadily through the liquid as the flask warmed over the Bunsen burner."
Regular plural formed by adding -s; standard in all varieties of English.
"The lab technician rinsed three flasks and set them on the drying rack."
Say 'fiasco' after an Italian waiter drops a bottle and you're being more literal than you think: 'fiasco' originally meant the flask-shaped wine bottle itself.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Etymology of flask
Flask entered English in the early modern period, borrowed via Romance languages from Medieval Latin 'flasco'. The Latin form itself is generally traced to a Germanic source — the same root that gives modern German 'Flasche' (bottle) — reflecting the reputation of Germanic glassware in the medieval period. Cognates and descendants of the same line include the Italian 'fiasco', literally a flask-shaped wine bottle, and the French-derived 'flagon'.
Related word forms
How flask is actually used
Flask is a neutral, everyday-to-technical word. In British English it is strongly associated with the vacuum flask for hot drinks; in American usage 'Thermos' (a brand) often replaces this sense colloquially. In laboratory contexts the word is precise and specific to glassware shapes.
Easily confused with flask
Flash means a sudden burst of light or something done very quickly, whereas flask is a liquid-holding container — the words differ by only one letter but are unrelated.