The Collaborative International Dictionary of English v.0.48:

Nausea \Nau"se*a\ (? or ?), n. [L., fr. Gr. ?, fr. nay^s ship.
   See Nave of a church, and cf. Noise.]
   Seasickness; hence, any similar sickness of the stomach
   accompanied with a propensity to vomit; qualm; squeamishness
   of the stomach; loathing.
   [1913 Webster]

WordNet (r) 3.0 (2006):

nausea
    n 1: the state that precedes vomiting [syn: nausea,
         sickness]
    2: disgust so strong it makes you feel sick

Moby Thesaurus II by Grady Ward, 1.0:

151 Moby Thesaurus words for "nausea":
   abhorrence, abomination, abscess, ague, airsickness, allergy,
   anemia, angst, anguish, ankylosis, anoxia, antagonism, antipathy,
   anxiety, apnea, asphyxiation, asthma, ataxia, atrophy, aversion,
   backache, barf, bleeding, blennorhea, boredom, cachexia, cachexy,
   car sickness, cheerlessness, chill, chills, cold sweat, colic,
   constipation, convulsion, coughing, creeping flesh, cyanosis,
   diarrhea, discomfort, discomposure, discontent, disgorgement,
   disgust, dislike, displeasure, disquiet, dissatisfaction,
   dizziness, dread, dropsy, dullness, dysentery, dyspepsia, dyspnea,
   edema, egesta, egestion, emaciation, emptiness, enmity, ennui,
   existential woe, fainting, fatigue, fever, fibrillation, flatness,
   flux, gagging, grimness, growth, hate, hatred, heaves, heaving,
   hemorrhage, high blood pressure, horror, hostility, hydrops,
   hypertension, hypotension, icterus, indigestion, inflammation,
   inquietude, insomnia, itching, jaundice, joylessness,
   labored breathing, lack of pleasure, loathing, low blood pressure,
   lumbago, mal de mer, malaise, marasmus, mortal horror,
   motion sickness, nasal discharge, necrosis, nongratification,
   nonsatisfaction, pain, painfulness, paralysis, pruritus, puke,
   qualm, qualmishness, queasiness, rash, regurgitation, repugnance,
   repulsion, rheum, savorlessness, sclerosis, seasickness, seizure,
   shock, shuddering, skin eruption, sneezing, sore, spasm, spew,
   spleen, squeamishness, staleness, tabes, tachycardia,
   tastelessness, tediousness, tedium, tumor, uncomfortableness,
   unease, uneasiness, unhappiness, unpleasure, unsatisfaction,
   upset stomach, vertigo, vexation of spirit, vomit, vomiting,
   vomition, wasting