The Collaborative International Dictionary of English v.0.48:

Sick \Sick\, a. [Compar. Sicker; superl. Sickest.] [OE. sek,
   sik, ill, AS. se['o]c; akin to OS. siok, seoc, OFries. siak,
   D. ziek, G. siech, OHG. sioh, Icel. sj?kr, Sw. sjuk, Dan.
   syg, Goth. siuks ill, siukan to be ill.]
   1. Affected with disease of any kind; ill; indisposed; not in
      health. See the Synonym under Illness.
      [1913 Webster]

            Simon's wife's mother lay sick of a fever. --Mark i.
                                                  30.
      [1913 Webster]

            Behold them that are sick with famine. --Jer. xiv.
                                                  18.
      [1913 Webster]

   2. Affected with, or attended by, nausea; inclined to vomit;
      as, sick at the stomach; a sick headache.
      [1913 Webster]

   3. Having a strong dislike; disgusted; surfeited; -- with of;
      as, to be sick of flattery.
      [1913 Webster]

            He was not so sick of his master as of his work.
                                                  --L'Estrange.
      [1913 Webster]

   4. Corrupted; imperfect; impaired; weakned.
      [1913 Webster]

            So great is his antipathy against episcopacy, that,
            if a seraphim himself should be a bishop, he would
            either find or make some sick feathers in his wings.
                                                  --Fuller.
      [1913 Webster]

   Sick bay (Naut.), an apartment in a vessel, used as the
      ship's hospital.

   Sick bed, the bed upon which a person lies sick.

   Sick berth, an apartment for the sick in a ship of war.

   Sick headache (Med.), a variety of headache attended with
      disorder of the stomach and nausea.

   Sick list, a list containing the names of the sick.

   Sick room, a room in which a person lies sick, or to which
      he is confined by sickness.

   Note: [These terms, sick bed, sick berth, etc., are also
         written both hyphened and solid.]
         [1913 Webster]

   Syn: Diseased; ill; disordered; distempered; indisposed;
        weak; ailing; feeble; morbid.
        [1913 Webster]

WordNet (r) 3.0 (2006):

sick headache
    n 1: a headache accompanied by nausea
    2: a severe recurring vascular headache; occurs more frequently
       in women than men [syn: migraine, megrim, sick
       headache, hemicrania]