The state of two planes parallel to each other; where two planes are equidistantly spaced in three dimensional space.

(n) An orientation control for geometric dimensioning and tolerancing. Parallelism is a condition in which a surface or an axis is equidistant at all points from a datum plane or datum axis, respectively. The distance between the feature and the datum is the tolerance value given in the control frame.

The condition that results when a surface, axis or centerplane is exactly parallel to a datum. Carry the GD&T Ultimate Pocket Guide with you on the job. It contains all these glossary terms and more.

refers to Earth's axis always pointing to the same place in space (Polaris); as Earth revolves, its axis is parallel to its previous position

used in GD&T, parallelism refers to the condition of a surface, line, or axis, which is equidistant at all points from a datum plane or axis