The Collaborative International Dictionary of English v.0.48:

Emphysema \Em`phy*se"ma\, n. [NL., from Gr. ? inflation, fr. ?
   to inflate; ? in + ? to blow: cf. F. emphys[`e]me.] (Med.)
   A swelling produced by gas or air diffused in the cellular
   tissue.
   [1913 Webster]

   Emphysema of the lungs, Pulmonary emphysema (Med.), a
      common disease of the lungs in which the air cells are
      distended and their partition walls ruptured by an
      abnormal pressure of the air contained in them.
      [1913 Webster]

WordNet (r) 3.0 (2006):

pulmonary emphysema
    n 1: an abnormal condition of the lungs marked by decreased
         respiratory function; associated with smoking or chronic
         bronchitis or old age [syn: emphysema, pulmonary
         emphysema]