Definition of thorax in English:

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Pronunciation: /ˈTHôrˌaks/

noun (plural thoraxes or thoraces /ˈTHôrəˌsēz/)

Anatomy & Zoology
1The part of the body of a mammal between the neck and the abdomen, including the cavity enclosed by the ribs, breastbone, and dorsal vertebrae, and containing the chief organs of circulation and respiration; the chest.
Example sentences
  • The lungs are contained within the paired pleural cavities in the thorax.
  • Lesions usually begin on the upper thorax and neck but may spread to the entire body.
  • Originating at the level of the sixth cervical vertebra, posterior to the cricoid cartilage, the esophagus passes through the thorax slightly to the right and behind the aortic arch and the left main stem bronchus.
1.1 Zoology The corresponding part of a bird, reptile, amphibian, or fish.
Example sentences
  • During April to June 2002, each captured adult was restrained on a Plexiglas board with narrow Velcro straps across the bird's thorax and adhesive tape to secure full extension of the wings.
  • As the bird lands and decelerates the weight of the pectoralis and sternocoricoideus muscles causes the sternum to swing ventrally, increasing the volume of the thorax.
  • All birds have an extensive air sac system in the thorax and abdomen.
1.2 Entomology The middle section of the body of an insect, between the head and the abdomen, bearing the legs and wings.
Example sentences
  • Upon emergence, adult female wasps were marked individually with small spots of paint on the ventral surface of the thorax between the wings.
  • Its limp, still-soft wings of cream and various browns, with touches of pink, were folded over its thorax and abdomen, which were covered with a light down.
  • These spots may be missing, but in all cases there is a small black triangle at the base of the wings near the thorax.


Late Middle English: via Latin from Greek thōrax.

Words that rhyme with thorax

borax, storax

For editors and proofreaders

Syllabification: tho·rax

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