Contact, n.
Etymology: [L. contactus, fr. contingere, -tactum, to touch on all sides. See Contingent.]
1. A close union or junction of bodies; a touching or meeting.
2. (Geom.)
The property of two curves, or surfaces, which meet, and at the point of meeting have a common direction.
3. (Mining)
1 more senses
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.
Shades of meaning
Fernald has no entry of its own for contact; he lists it under collision.
Where he writes about it:
Collision, the act or fact of striking violently together, is the result of motion or action, and is sudden and momentary; contact may be a condition of rest, and be continuous and permanent; collision is sudden and violent contact. — from collision