Webster's Revised Unabridged Dictionary · 1913

Ictus

Ictus , noun

[Latin, from icere, ictum, to strike.]

1.
(Prosody) The stress of voice laid upon accented syllable of a word. Compare Arsis.
2.
(Medicine) A stroke or blow, as in a sunstroke, the sting of an insect, pulsation of an artery, etc.