Ballpoint (pen). (n.d.). In YourDictionary. Retrieved from https://www.yourdictionary.com/ballpoint-pen
(plural ballpoint pens)
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).
English Wiktionary. Available under CC-BY-SA license.