Flask/flæsk/ Definition 1 of 3Pro Tip 1/3Scientific Usage The term 'flask' is commonly used in scientific contexts, particularly in chemistry. The scientist swirled the blue liquid in the flask carefully. Pro Tip 2/3Shape Specific In a lab, flasks have distinct shapes, like the Erlenmeyer flask, which is conical. Please grab that conical flask for our experiment. Pro Tip 3/3Not Always Glass While often made of glass, flasks can also be plastic or metal in laboratories. He labeled the plastic flasks before starting.