The Collaborative International Dictionary of English v.0.48:

Asthma \Asth"ma\ (?; 277), n. [Gr. ? short-drawn breath, fr. ?
   to blow, for ?: cf. Skr. v[=a], Goth. waian, to blow, E.
   wind.] (Med.)
   A disease, characterized by difficulty of breathing (due to a
   spasmodic contraction of the bronchi), recurring at
   intervals, accompanied with a wheezing sound, a sense of
   constriction in the chest, a cough, and expectoration.
   [1913 Webster]

WordNet (r) 3.0 (2006):

asthma
    n 1: respiratory disorder characterized by wheezing; usually of
         allergic origin [syn: asthma, asthma attack, bronchial
         asthma]

Moby Thesaurus II by Grady Ward, 1.0:

144 Moby Thesaurus words for "asthma":
   Asiatic flu, Hong Kong flu, abscess, acute bronchitis, adenoiditis,
   ague, allergen, allergic disorder, allergy, aluminosis,
   amygdalitis, anemia, ankylosis, anoxia, anthracosilicosis,
   anthracosis, apnea, asbestosis, asphyxiation, ataxia, atrophy,
   atypical pneumonia, backache, bituminosis, black lung, bleeding,
   blennorhea, bronchial pneumonia, bronchiectasis, bronchiolitis,
   bronchitis, bronchopneumonia, cachexia, cachexy, catarrh,
   chalicosis, chill, chills, chronic bronchitis, cold, colic,
   collapsed lung, common cold, coniosis, conjunctivitis,
   constipation, convulsion, coryza, cosmetic dermatitis, coughing,
   croup, croupous pneumonia, cyanosis, diarrhea, dizziness,
   double pneumonia, dropsy, dry pleurisy, dysentery, dyspepsia,
   dyspnea, eczema, edema, emaciation, emphysema, empyema,
   epidemic pleurodynia, fainting, fatigue, fever, fibrillation,
   fibrinous pneumonia, flu, flux, grippe, growth, hay fever,
   hemorrhage, high blood pressure, hives, hydrops, hypertension,
   hypotension, icterus, indigestion, inflammation, influenza,
   insomnia, itching, jaundice, la grippe, labored breathing,
   laryngitis, lipoid pneumonia, lobar pneumonia, low blood pressure,
   lumbago, lung cancer, lung fever, marasmus, nasal discharge,
   nausea, necrosis, pain, paralysis, pharyngitis, pleurisy,
   pleuritis, pneumococcal pneumonia, pneumoconiosis, pneumonia,
   pneumonic fever, pneumothorax, pollinosis, pruritus, quinsy, rash,
   rheum, rose cold, sclerosis, seizure, shock, siderosis, silicosis,
   skin eruption, sneezing, sore, sore throat, spasm, swine flu,
   tabes, tachycardia, the sniffles, the snuffles, tonsilitis, tumor,
   upset stomach, urticaria, vertigo, virus pneumonia, vomiting,
   wasting, wet pleurisy, whooping cough