Meaning of sodium-vapor lamp

so'dium-va•por lamp"

Pronunciation: (sō'dē-um-vā"pur), [key]
— Elect. Elect.
  1. an electric lamp in which sodium vapor is activated by current passing between two electrodes, producing a yellow, glareless light: used on streets and highways. Also called
Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease.