mes·o·tho·rax (měz'ə-thôr'āks', -thōr'-, měs'-) n.
pl.mes·o·tho·rax·es or mes·o·tho·ra·ces (-thôr'ə-sēz', -thōr'-) The middle of the three divisions of the thorax of an insect, bearing the middle pair of legs and the first pair of wings. mes'o·tho·rac'ic (-thô-rās'ĭk, -thō-) adj.