Stedman's Medical Dictionary

pylorus , pl. pylori (p-lrs, p-lr) [TA]
  1. A muscular or myovascular device to open (musculus dilator) and to close (musculus sphincter) an orifice or the lumen of an organ.
  2. The muscular tissue surrounding and controlling the aboral outlet of the stomach.
[L. fr. G. pylros, a gatekeeper, the pylorus, fr. pyl, gate, + ouros, a warder]