[1] : The Collaborative International Dictionary of English v.0.48

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 vertebrae more
   or less consolidated.
   1913 webster
see also:
coccyges 

[2] : WordNet (r) 2.0

coccyx
     n : the end of the vertebral column in humans and tailless apes
         syn: tail bone
     also: coccyges pl
see also:
tail bone coccyges 

Coccyx >> C Words
Coccyx, definition of term: Coccyx
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