The Collaborative International Dictionary of English v.0.48:

Trachea \Tra"che*a\, n.; pl. Tracheae. [NL.,from L. trachia,
   Gr. trachei^a (sc. ? windpipe), from ? rough, rugged: cf. F.
   trach['e]e.]
   [1913 Webster]
   1. (Anat.) The windpipe. See Illust. of Lung.
      [1913 Webster]

   2. (Zool.) One of the respiratory tubes of insects and
      arachnids.
      [1913 Webster]

   3. (Bot.) One of the large cells in woody tissue which have
      spiral, annular, or other markings, and are connected
      longitudinally so as to form continuous ducts.
      [1913 Webster]

WordNet (r) 3.0 (2006):

trachea
    n 1: membranous tube with cartilaginous rings that conveys
         inhaled air from the larynx to the bronchi [syn: trachea,
         windpipe]
    2: one of the tubules forming the respiratory system of most
       insects and many arachnids