What does "contact" mean?

Contact: (Geom.) The property of two curves, or surfaces, which meet, and at the point of meeting have a common direction.

Additional senses

  1. 2.(Mining) The plane between two adjacent bodies of dissimilar rock. Raymond. Contact level, a delicate level so pivoted as to tilt when two parts of a measuring apparatus come into contact with each other; -- used in precise determinations of lengths and in the accurate graduation of instruments.

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