The Collaborative International Dictionary of English v.0.48:

Cough \Cough\ (k?f), v. i. [imp. & p. p. Coughed (k?ft); p.
   pr. & vb. n. Coughing.] [Cf. D. kuchen, MHG. k?chen to
   breathe, G. keuchen to pant, and E. chincough, the first part
   of which is prob. akin to cough; cf. also E. choke.]
   To expel air, or obstructing or irritating matter, from the
   lungs or air passages, in a noisy and violent manner.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Cough \Cough\, v. t.
   1. To expel from the lungs or air passages by coughing; --
      followed by up; as, to cough up phlegm.
      [1913 Webster]

   2. To bring to a specified state by coughing; as, he coughed
      himself hoarse.
      [1913 Webster]

   To cough down, to silence or put down (an objectionable
      speaker) by simulated coughing.
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Cough \Cough\, n. [Cg. D. kuch. See Cough, v. i. ]
   1. A sudden, noisy, and violent expulsion of air from the
      chest, caused by irritation in the air passages, or by the
      reflex action of nervous or gastric disorder, etc.
      [1913 Webster]

   2. The more or less frequent repetition of coughing,
      constituting a symptom of disease.
      [1913 Webster]

   Stomach cough, Ear cough, cough due to irritation in the
      stomach or ear.
      [1913 Webster]

WordNet (r) 3.0 (2006):

cough
    n 1: a sudden noisy expulsion of air from the lungs that clears
         the air passages; a common symptom of upper respiratory
         infection or bronchitis or pneumonia or tuberculosis [syn:
         cough, coughing]
    v 1: exhale abruptly, as when one has a chest cold or
         congestion; "The smoker coughs all day"

Moby Thesaurus II by Grady Ward, 1.0:

54 Moby Thesaurus words for "cough":
   Aqua-Lung, artificial respiration, aspiration, asthmatic wheeze,
   blow, breath, breath of air, breathe, breathe hard, breathe in,
   breathe out, breathing, broken wind, exhalation, exhale, exhaust,
   expel, expiration, expire, exsufflation, gasp, gulp, hack, hiccup,
   huff, inhalation, inhalator, inhale, inspiration, inspire,
   insufflation, iron lung, mouth-to-mouth resuscitation, oxygen mask,
   oxygen tent, pant, puff, respiration, respire, scuba, sigh, sneeze,
   sniff, sniffle, snore, snoring, snort, snuff, snuffle,
   sternutation, stertor, suspiration, wheeze, wind