tra-, tract-, trac-, -tractive, -traction, -tracting, treat-, trai-

1. A company or person with a formal contract to do a specific job, supplying labor and materials; as well as, providing and overseeing staff if necessary.
2. Someone who agrees to furnish materials or to perform services at a specified price; especially, for construction work.
3. Something that contracts; especially, a muscle in the body.

1. A law which describes the electric force between charged objects which states that:

• Like charges repel each other and unlike charges attract each other.
• The attraction or repulsion acts along the line between the two charges.
• The size of the force varies inversely as the square of the distance between the two charges.
• The size of the force is proportional to the value of each charge.

2. In physics, a law stating that the electrostatic force between two charged bodies is proportional to the product of the amount of charge on the bodies divided by the square of the distance between them.

If the bodies are oppositely charged, one positive and one negative, they are attracted toward one another; if the bodies are similarly charged, both positive or both negative, the force between them is repulsive.

Coulomb's law applies only when the charged bodies are much smaller than the distance separating them and therefore can be treated approximately as point charges.

A type of cranioclast (instrument for crushing the head of a fetus, to facilitate delivery in difficult eases) which can also be used to apply traction to the fetus.

Removal of cataracts by the adhesion of a freezing probe to the lens; now rarely done: Cryoextraction is accomplished with an instrument (cryoprobe) whose extremely cold tip forms an adhesion (iceball) with the lens, thus permitting removal of the lens.

An surgical instrument (cryoprobe), artificially cooled, for extraction of the lens by freezing contact: Dr. Smith explained to his students that a cryoextractor used to be used in his clinic for removing the lens of a person's eye by the means of extreme coldness.