The Collaborative International Dictionary of English v.0.48:

Asthmatic \Asth*mat"ic\, Asthmatical \Asth*mat"ic*al\, a. [L.
   asthmaticus, Gr. ?.]
   Of or pertaining to asthma; as, an asthmatic cough; liable
   to, or suffering from, asthma; as, an asthmatic patient. --
   Asth*mat"ic*al*ly, adv.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Asthmatic \Asth*mat"ic\, n.
   A person affected with asthma.
   [1913 Webster]

WordNet (r) 3.0 (2006):

asthmatic
    adj 1: relating to breathing with a whistling sound [syn:
           asthmatic, wheezing, wheezy]
    n 1: a person suffering from asthma; "she is a chronic
         asthmatic"; "the painful gasps of a dying asthmatic"

Moby Thesaurus II by Grady Ward, 1.0:

27 Moby Thesaurus words for "asthmatic":
   breathing, errhine, expiratory, heaving, huffing, inspiratory,
   nasal, panting, pneumonic, puffing, pulmonary, pulmonic,
   respiratory, rhinal, sneezy, sniffling, sniffly, sniffy, snoring,
   snorting, snuffling, snuffly, snuffy, sternutatory, stertorous,
   wheezing, wheezy