xenobiote Any biotum displaced from its normal habitat; a chemical foreign to a biological system.

xeric Characterized by or pertaining to conditions of scanty moisture supply.

Xeriscape™ Landscaping that involves seven principles: proper planning and design, soil analysis and improvement, practical turf areas, appropriate plant selection, efficient irrigation, mulching, and appropriate maintenance.

xerophyte A plant that can subsist with a small amount of moisture, such as a desert plant.

x-ray Radiant energy of short wave length produced by high speed electron striking a metal target in a vacuum. X-rays are similar in wavelength and frequency to gamma rays, which originate in the nucleus of an atom. Also know as roentgen rays.

X-ray diffraction A direct corrosion monitoring method that identifies the scale constituents on a pipe evaluation of a diffraction pattern.