The Collaborative International Dictionary of English v.0.48:

Tabes \Ta"bes\ (t[=a]"b[=e]z), n. [L., a wasting disease.]
   (Med.)
   Progressive emaciation of the body, accompanied with hectic
   fever, with no well-marked local symptoms.
   [1913 Webster]

   Tabes dorsalis (t[=a]"b[=e]z d[^o]r*s[=a]"l[i^]s) [NL.,
      tabes of the back], locomotor ataxia; -- sometimes called
      simply tabes.

   Tabes mesenterica[NL., mesenteric tabes], a wasting disease
      of childhood characterized by chronic inflammation of the
      lymphatic glands of the mesentery, attended with caseous
      degeneration.
      [1913 Webster]

WordNet (r) 3.0 (2006):

tabes
    n 1: wasting of the body during a chronic disease

Moby Thesaurus II by Grady Ward, 1.0:

113 Moby Thesaurus words for "tabes":
   French disease, Spanish pox, VD, abscess, acquired syphilis, ague,
   anemia, ankylosis, anoxia, apnea, asphyxiation, asthma, ataxia,
   atrophy, attenuation, backache, balanitis gangrenosa, bleeding,
   blennorhea, cachexia, cachexy, cerebral tabes, chancre, chancroid,
   chill, chills, clap, claps, climatic bubo, colic,
   congenital syphilis, constipation, constitutional syphilis,
   convulsion, coughing, cyanosis, diarrhea, dizziness, dose,
   dose of clap, dropsy, dysentery, dyspepsia, dyspnea, edema,
   emaceration, emaciation, fainting, fatigue, fever, fibrillation,
   fifth venereal disease, flux, general paresis, gonorrhea,
   granuloma inguinale, granuloma venereum, great pox, growth,
   hard chancre, hemorrhage, high blood pressure, hydrops,
   hypertension, hypotension, icterus, indigestion, inflammation,
   insomnia, itching, jaundice, labored breathing, latent syphilis,
   locomotor ataxia, low blood pressure, lumbago, marasmus,
   morbus Gallicus, nasal discharge, nausea, necrosis, pain,
   paralysis, paralytic dementia, paresis, pox, pruritus,
   pudendal ulcer, rash, rheum, sclerosis, seizure, shock,
   simple chancre, skin eruption, sneezing, social disease,
   soft chancre, sore, spasm, syph, syphilis,
   syphilitic meningoencephalitis, tabes dorsales, tachycardia,
   tertiary syphilis, tropical bubo, tumor, upset stomach,
   venereal disease, vertigo, vomiting, wasting