(noun; plural tracheae
; Latin trachia
, windpipe): 1. The windpipe.
2. (Arthropoda: Chelicerata) For Arachnida, see tube, sieve trachea.
3. (Arthropoda: Insecta) The larger tubes of the respiratory system, lined with taenidia, opening to the outside through the spiracles and terminating internally in the tracheoles.
4. (Mollusca: Gastropoda) see ctenidia.
5. (Onychophora) In Peripatus, short tubes without spiral thickenings, neither branching nor anastomosing, opening externally through numerous minute spiracles.