noun
1. : a hollow core through which water circulates in a founding mold and which is used (as in casting a cannon) for cooling the interior of a casting more rapidly than the outside while the metal is solidifying
2.
a. : a physiological disease of fruits (as apples) in which parts of the inner tissues especially close to the core become water-soaked, hard, and glassy
b. : a similar disease of turnips caused by boron deficiency