/
ˈθɔːraks/
n.
 (pl. thoraces  
/ˈθɔːrəsiːz/
 or thoraxes)
 Anatomy  & 
Zoology  the part of the body of a mammal between the neck and the abdomen, including the cavity enclosed by the ribs, breastbone, and dorsal vertebrae. 
▸Zoology  the corresponding part of a bird, reptile, amphibian, or fish.
 ▸Entomology  the middle section of the body of an insect, between the head and the abdomen, bearing the legs and wings.
Etymology
ME: via L. from Gk thōrax.