ictus

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun Medicine A sudden attack, blow, stroke, or seizure.
• noun The accent that falls on a stressed syllable in a line of scanned verse.

from The Century Dictionary.

• noun A stroke: as, ictus solis, sunstroke.
• noun In prosody and music, rhythmical or metrical stress; additional intensity of utterance or delivery distinguishing one time or syllable in a foot or series from the others.
• noun in which the accent is marked and the syllables bearing the ictus are italicized. The part of a foot on which the ictus falls is called the thesis (but see arsis). In a dipody one ictus is stronger than the other. In a colon the ictus of one measure dominates all others. A subordinate ictus can also accompany the principal ictus within the same foot.

from the GNU version of the Collaborative International Dictionary of English.

• noun (Pros.) The stress of voice laid upon accented syllable of a word. Cf. arsis.
• noun (Med.) A stroke or blow, as in a sunstroke, the sting of an insect, pulsation of an artery, etc.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun the pulse
• noun medicine A sudden attack, blow, stroke, or seizure, as in a sunstroke, the sting of an insect, pulsation of an artery, etc.
• noun The stress of voice laid upon an accented syllable of a word. Compare arsis.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun a sudden occurrence (or recurrence) of a disease