Source : Webster's Revised Unabridged Dictionary (1913)

Ictus \Ic"tus\, n. [L., fr. icere, ictum, to strike.]
   1. (Pros.) The stress of voice laid upon accented syllable of
      a word. Cf. {Arsis}.

   2. (Med.) A stroke or blow, as in a sunstroke, the sting of
      an insect, pulsation of an artery, etc.

Source : WordNet®

ictus
     n : a sudden occurrence (or recurrence) of a disease; "he
         suffered an epileptic seizure" [syn: {seizure}, {raptus}]