zoanthushttp://www.oed.com/dictionary/zoanthus_n%3Ftab%3Dmeaning_and_usezoanthus, n.
First published 1921; not fully revised

zoanthusnoun

Zoology.
  1. 1841–
    1. 1841
      A small Zoanthus or other naked zoophyte.
      T. R. Jones, General Outline of Animal Kingdom iii. 37

Originally published as part of the entry for zoantharian, adj. & n.

zoantharian, adj. & n. was first published in 1921; not fully revised.