Source : Webster's Revised Unabridged Dictionary (1913)

Pertussis \Per*tus"sis\, n. [NL., fr. L. per through, very +
   tussis cough.] (Med.)
   The whooping cough.

Source : WordNet®

pertussis
     n : a disease of the respiratory mucous membrane [syn: {whooping
         cough}]