What term refers to the permissible variation in a dimension?

The term that refers to the permissible variation in a dimension is tolerance. In engineering and manufacturing, tolerance defines the acceptable range of variation for a specific measurement. It indicates the limits within which a part or feature can deviate from a specified dimension and still be considered acceptable. Tolerances are crucial for ensuring proper fit, function, and interchangeability of components in mechanical assemblies.

For example, if a shaft is designed to be 50 mm in diameter, a tolerance might specify that the actual diameter can vary between 49.5 mm and 50.5 mm. This allows for slight variations that can occur during the manufacturing process while ensuring that the components will still function correctly when assembled.

The other terms listed do not accurately represent the concept of permissible variation in dimensions. Percentage typically refers to a fraction of a whole expressed in hundredths and does not inherently relate to dimensional variation. Standard deviation is a statistical measure of the amount of variation or dispersion in a set of values, and while it relates to variability, it is not specifically used to define allowable variations in manufacturing tolerances. Variance, like standard deviation, is also a statistical term that measures variability within a set of data but does not pertain to tolerances in dimensions.