WordNet (r) 3.0 (2006):

hypotension
    n 1: abnormally low blood pressure [ant: high blood pressure,
         hypertension]

Moby Thesaurus II by Grady Ward, 1.0:

72 Moby Thesaurus words for "hypotension":
   abscess, ague, anemia, ankylosis, anoxia, apnea, asphyxiation,
   asthma, ataxia, atrophy, backache, bleeding, blennorhea, cachexia,
   cachexy, chill, chills, colic, constipation, convulsion, coughing,
   cyanosis, diarrhea, dizziness, dropsy, dysentery, dyspepsia,
   dyspnea, edema, emaciation, fainting, fatigue, fever, fibrillation,
   flux, growth, hemorrhage, high blood pressure, hydrops,
   hypertension, icterus, indigestion, inflammation, insomnia,
   itching, jaundice, labored breathing, low blood pressure, lumbago,
   marasmus, nasal discharge, nausea, necrosis, pain, paralysis,
   pruritus, rash, rheum, sclerosis, seizure, shock, skin eruption,
   sneezing, sore, spasm, tabes, tachycardia, tumor, upset stomach,
   vertigo, vomiting, wasting