The Collaborative International Dictionary of English v.0.48:

larynx \lar"ynx\ (l[a^]r"[i^][ng]ks; 277), n. [NL. from Gr.
   la`rygx, la`ryggos.] (Anat.)
   The expanded upper end of the windpipe or trachea, connected
   with the hyoid bone or cartilage. It contains the vocal
   cords, which produce the voice by their vibrations, when they
   are stretched and a current of air passes between them. The
   larynx is connected with the pharynx by an opening, the
   glottis, which, in mammals, is protected by a lidlike
   epiglottis.
   [1913 Webster]

   Note: In the framework of the human larynx, the thyroid
         cartilage, attached to the hyoid bone, makes the
         protuberance on the front of the neck known as Adam's
         apple, and is articulated below to the ringlike cricoid
         cartilage. This is narrow in front and high behind,
         where, within the thyroid, it is surmounted by the two
         arytenoid cartilages, from which the vocal cords pass
         forward to be attached together to the front of the
         thyroid. See Syrinx.
         [1913 Webster]

WordNet (r) 3.0 (2006):

larynx
    n 1: a cartilaginous structure at the top of the trachea;
         contains elastic vocal cords that are the source of the
         vocal tone in speech [syn: larynx, voice box]

Moby Thesaurus II by Grady Ward, 1.0:

27 Moby Thesaurus words for "larynx":
   alveolar ridge, alveolus, apex, arytenoid cartilages, back, blade,
   dorsum, hard palate, lips, nasal cavity, oral cavity, palate,
   pharyngeal cavity, pharynx, soft palate, speech organ, syrinx,
   teeth, teeth ridge, tip, tongue, velum, vocal chink, vocal cords,
   vocal folds, vocal processes, voice box