trachea UK /tɹəˈkiː.ə/US /ˈtɹeɪ.ki.ə/ noun3 •A thin-walled, cartilaginous tube connecting the larynx to the bronchi. •One of the cuticle-lined primary tubes in the respiratory system of an insect, which extend throughout its body. •(old-fashioned) The xylem vessel. formstracheae · tracheae · tracheas