Source : Webster's Revised Unabridged Dictionary (1913)

Est \Est\, n. & adv.
   East. [Obs.] --Chaucer.

Source : WordNet®

EST
     n : standard time in the 5th time zone west of Greenwich,
         reckoned at the 75th meridian; used in the eastern United
         States [syn: {Eastern Time}, {Eastern Standard Time}]