from The American Heritage® Dictionary of the English Language, 4th Edition

  • n. A small triangular bone at the base of the spinal column in humans and tailless apes, consisting of several fused rudimentary vertebrae. Also called tailbone.

from Wiktionary, Creative Commons Attribution/Share-Alike License

  • n. The final fused vertebrae at the base of the spine.

from the GNU version of the Collaborative International Dictionary of English

  • n. The end of the vertebral column beyond the sacrum in man and tailless monkeys. It is composed of several vertebræ more or less consolidated.

from The Century Dictionary and Cyclopedia

  • n. In human anatomy, the part of the spinal column consisting of the last four bones, the caudal vertebræ or tail-bones, which are stunted and usually ankylosed together. See cut under skeleton.
  • n. In comparative anatomy and zoology, the caudal vertebræ, when few and small, or ankylosed together; the bony tail itself, when short, as in a bird.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

  • n. the end of the vertebral column in humans and tailless apes


New Latin, from Greek kokkūx, cuckoo, coccyx (from its resemblance to a cuckoo's beak).
(American Heritage® Dictionary of the English Language, Fourth Edition)
From Ancient Greek κόκκυξ (kokkyx, "cuckoo"), referring to the curved shape of a cuckoo's beak when viewed from the side. (Wiktionary)



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  • Public transport always leaves me with a sore one of these.

    August 13, 2009

  • See iroquoisy.

    December 11, 2008

  • First word that I found with random word after listing geococcyx. *wonders if this is part of bilby's trap*

    December 11, 2008

  • I really recommend that you don't go running on smooth tiles while wearing socks on a rainy day. Sitting down suddenly and hard on your tail bone when your feet go from under you hurts!

    November 10, 2008