ballpoint pen

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

• noun A pen, similar in size and shape to a pencil, having an internal chamber filled with a viscous, quick-drying ink that is dispensed at the tip during use by the rolling action of a metal sphere (around 0.7 mm to 1 mm in diameter).

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

• noun a pen that has a small metal ball as the point of transfer of ink to paper