Source : Webster's Revised Unabridged Dictionary (1913)

Coccyx \Coc"cyx\, n.; pl. L. {Coccyges}. [L., cuckoo, Gr. ?,
   cuckoo, coccyx. So called from its resemblance to the beak of
   a cuckoo.] (Anat.)
   The end of the vertebral column beyond the sacrum in man and
   tailless monkeys. It is composed of several vertebr[ae] more
   or less consolidated.

Source : WordNet®

coccyx
     n : the end of the vertebral column in humans and tailless apes
         [syn: {tail bone}]
     [also: {coccyges} (pl)]