What is a scale?
A small, thin, often flattened plant structure, such as one of the modified leaves that cover a tree bud or one of the structures that contain the reproductive organs on the cones of a conifer.
A scale insect.
A plant disease or infestation caused by scale insects.
A flaky oxide film formed on a metal, as on iron, that has been heated to high temperatures.
A hard mineral coating that forms on the inside surface of boilers, kettles, and other containers in which water is repeatedly heated. See the scale have many definitions.