Source : Webster's Revised Unabridged Dictionary (1913)

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.

Source : WordNet®

coughing
     n 1: the act of exhaling air suddenly with a noise [syn: {cough}]
     2: sudden 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}]