One of the many small platelike dermal or epidermal structures that characteristically form the external covering of fishes, reptiles, and certain mammals. A similar part, such as one of the minute structures overlapping to form the covering on the wings of butterflies and moths. Pathology A dry thin flake of epidermis shed from the skin. A small thin piece. Botany A small, thin, usually dry, often appressed plant structure, such as any of the protective leaves that cover a tree bud or the bract that subtends a flower in a sedge spikelet. 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 flake of rust. A hard mineral coating that forms on the inside surface of boilers, kettles, and other containers in which water is repeatedly heated. To clear or strip of scale or scales: Scale and clean the fish. To remove in layers or scales: scaled off the old paint. To cover with scales; encrust. To throw (a thin flat object) so that it soars through the air or skips along the surface of water. Dentistry To remove (tartar) from tooth surfaces with a pointed instrument. Australian To cheat; swindle. Australian To ride on (a tram or train, for example) without paying the fare. To come off in scales or layers; flake. To become encrusted. A system of ordered marks at fixed intervals used as a reference standard in measurement: a ruler with scales in inches and centimeters. An instrument or device bearing such marks. A standard of measurement or judgment; a criterion. A proportion used in determining the dimensional relationship of a representation to that which it represents: a world map with a scale of 1:4,560,000. A calibrated line, as on a map or an architectural plan, indicating such a proportion. Proper proportion: a house that seemed out of scale with its surroundings.