Meaning of FLASK in English
(n.) The wooden or iron frame which holds the sand, etc., forming the mold used in a foundry; it consists of two or more parts; viz., the cope or top; sometimes, the cheeks, or middle part; and the drag, or bottom part. When there are one or more cheeks, the flask is called a three part flask, four part flask, etc.
Webster's English dictionary. Английский словарь Webster. 2012