zone-axishttp://www.oed.com/dictionary/zone-axis_n%3Ftab%3Dmeaning_and_usezone-axis, n.
First published 1921; not fully revised

zone-axisnoun

  1. 1878–
    1. 1878
      The zone, the zone axis, and the zone plane are all denoted by the same symbol, namely (U V W).
      H. P. Gurney, Crystallography 22

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

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