WordNet (r) 3.0 (2006):

sick person
    n 1: a person suffering from an illness [syn: sick person,
         diseased person, sufferer]

Moby Thesaurus II by Grady Ward, 1.0:

18 Moby Thesaurus words for "sick person":
   apoplectic, arthritic, case, consumptive, dyspeptic, epileptic,
   incurable, inpatient, invalid, outpatient, patient, rheumatic,
   shut-in, spastic, sufferer, terminal case, the sick,
   valetudinarian