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coccyx Syllabification: coc·cyx
Pronunciation: /ˈkäksiks/

Definition of coccyx in English:

noun (plural coccygesˈkäksəˌjēz or coccyxesˈkäksiksiz)

A small, triangular bone at the base of the spinal column in humans and some apes, formed of fused vestigial vertebrae.
Example sentences
  • The sacrum itself represents 5 fused bones, and the coccyx another vestigial 2-3 or more - the remains of the ancestral tail.
  • The spinal column is composed of seven cervical vertebrae, twelve thoracic vertebrae, five lumbar vertebrae, the bony sacrum, and the coccyx.
  • Many of my patients have pressure ulcers on the coccyx or sacrum.


Pronunciation: /käkˈsijēəl/
Example sentences
  • The usual grouping formula of 7 cervical, 12 thoracic, 5 lumbar, 5 sacral, and 4 coccygeal vertebrae is found in only about 20% of individuals studied.
  • The lumbosacral plexus is formed by the union of the anterior primary divisions of the lumbar, sacral, and coccygeal nerves.
  • The fifth sacral and the coccygeal nerves (when present) are located within the dural cavity.


Late 16th century: via Latin from Greek kokkux 'cuckoo' (because the shape of the human bone resembles the cuckoo's bill).

  • Your coccyx is the small triangular bone at the base of your spine. The name comes via Latin from Greek kokkux ‘cuckoo’, because the shape of this bone looks like a cuckoo's beak.

Definition of coccyx in:
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