Pronunciation: (gärd'rāl"), [key]
1. Also,guard'rail"ing.a protective railing, as along a road or stairway.
2. Railroads.a rail laid parallel to a track to prevent derailment or to keep derailed rolling stock from leaving the roadbed.
Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease.