Mountain Standard Time[mounˈtən]
Mountain Standard Time definition by Webster's New World
Webster's New World College Dictionary Copyright © 2010 by Wiley Publishing, Inc., Cleveland, Ohio. Used by arrangement with John Wiley & Sons, Inc.
a standard time used in the zone which includes the Rocky Mountain region of the U.S. corresponding to the mean solar time of the 105th meridian west of Greenwich, England: it is seven hours behind Greenwich time
Mountain Standard Time definition by American Heritage Dictionary
noun Abbr. MST
Standard time in the seventh time zone west of Greenwich, England, reckoned at 105° west and used in the Rocky Mountain states of the United States. Also called Mountain Time.