firm ball stage [furm bawl steyj] noun
A phrase referring to a stage of cooked sugar, when a drop of sugar syrup placed in cold water will form a firm but pliable ball, which can be assessed between the fingertips. More specifically, the ball will not flatten when you take it out of the water; it will remain malleable but will flatten when squeezed firmly.
On a candy thermometer, the firm ball stage is between 244° and 248° Fahrenheit. This stage is used in many confectionary recipes, such as caramels.
Any time you are working with hot sugar, be sure to have a bowl of ice water at hand, as spilled hot sugar can burn severely. In the event that you get hot sugar on your skin, immerse it quickly in the iced water to literally lower the temperature of your skin.