cap screw

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun A long-threaded bolt, usually with a square head, used in fastening machine parts.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun A screw that is threaded along the entire length of the shaft and has a cap which is intended to rest against the side of the outermost material being screwed together when the screw has been screwed in to its maximum extent.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun a threaded screw for machine parts; screws into a tapped hole