zone-timehttp://www.oed.com/dictionary/zone-time_n%3Ftab%3Dmeaning_and_usezone time, n.
First published 1921; not fully revised

zone timenoun

  1. 1908–
    Mean solar time at the standard meridian on which the local time zone is based, taken as the standard time throughout the zone (cf. Zulu n. & adj.).
    1. 1908
      The Eighteen Provinces roughly extend from..longitude 98° to 122° E., comprising the seventh and eighth hours of the Zone time east of Greenwich.
      H. B. Morse, Trade Chinese Empire viii. 203
    2. 1930
      The passengers wonder whether they should retire by Greenwich or zone time.
      Daily Express 16 August 1/3
    3. 1981
      A vessel's chronometer or watch is not generally adjusted or altered at any time while the vessel is at sea, but her clock is altered as she moves through each zone in such a way that it should always be indicating the correct Zone Time for the vessel's position.
      G. Watkins, Exercises in Astro-navigation ii. 22

Originally published as part of the entry for zone, n.

zone, n. was first published in 1921; not fully revised.