The Collaborative International Dictionary of English v.0.48:

Hectic \Hec"tic\, a. [F. hectique, Gr. ? habitual, consumptive,
   fr. ? habit, a habit of body or mind, fr. ? to have; akin to
   Skr. sah to overpower, endure; cf. AS. sige, sigor, victory,
   G. sieg, Goth. sigis. Cf. Scheme.]
   1. Habitual; constitutional; pertaining especially to slow
      waste of animal tissue, as in consumption; as, a hectic
      type in disease; a hectic flush.
      [1913 Webster]

   2. In a hectic condition; having hectic fever; consumptive;
      as, a hectic patient.
      [1913 Webster]

   Hectic fever (Med.), a fever of irritation and debility,
      occurring usually at a advanced stage of exhausting
      disease, as a in pulmonary consumption.
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Hectic \Hec"tic\, n.
   1. (Med.) Hectic fever.
      [1913 Webster]

   2. A hectic flush.
      [1913 Webster]

            It is no living hue, but a strange hectic. --Byron.
      [1913 Webster]

WordNet (r) 3.0 (2006):

hectic
    adj 1: marked by intense agitation or emotion; "worked at a
           feverish pace" [syn: feverish, hectic]

Moby Thesaurus II by Grady Ward, 1.0:

122 Moby Thesaurus words for "hectic":
   agitated, at fever pitch, bloom, blooming, blowzed, blowzy, blush,
   blushing, boiling, boiling over, burning, burning with excitement,
   burnt, bustling, busy, calenture, chaotic, childbed fever,
   coloring, continued fever, crimsoning, delirious, delirium,
   eruptive fever, excited, fanatical, febricity, febrile, febrility,
   fervent, fervid, fever, fever heat, fevered, feverish,
   feverishness, feverous, fieriness, fiery, fire, flaming, florid,
   flush, flushed, flushing, frantic, frenetic, frenzied,
   full-blooded, furious, glow, glowing, heat, heated, hectic fever,
   hectic flush, het up, hot, hyperactive, hyperkinetic, hyperpyretic,
   hyperpyrexia, hyperthermia, hyperthermic, hysteric, in a fever,
   in rut, incandescence, infatuated, inflamed, insane,
   intermittent fever, intrusive, mad, mantling, officious,
   overanxious, overdesirous, overeager, overenthusiastic,
   overzealous, passionate, perfervid, protein fever, puerperal fever,
   pyretic, pyrexia, red-complexioned, red-faced, red-fleshed,
   red-hot, reddening, redness, relapsing fever, remittent,
   remittent fever, riotous, rosiness, rosy, rosy-cheeked,
   rubefacient, rubescence, rubicund, ruddy, ruddy-complexioned,
   ruddy-faced, rufescence, rushed, sanguine, seething,
   sexually excited, steaming, steamy, sunburned, ultrazealous,
   urethral fever, vaccinal fever, warm, water fever, whiteness, wild,
   wound fever