1. A proportion between two sets of dimensions, as between those of a drawing and its original; for example, the scale of a drawing may be expressed as 1/4 inch = one foot. 2. A measuring tool used by architects and engineers in preparing drawings to a proportionate scale. 3. To measure a drawing with a scale. 4. Either pan or tray of a balance. 5. To climb, as a ladder. 6. A series of graduated marked spaces for measuring something, as on a thermometer. 7. Rust occurring in thin layers. 8. Hard deposit of minerals on heater coils and pool surfaces.