What is the meaning of Ictus?

The pulse.

A sudden attack, blow, stroke, or seizure, as in a sunstroke, the sting of an insect, pulsation of an artery, etc.

The stress of voice laid upon an accented syllable of a word. Compare arsis.

In conducting, the indication of a musical event, most often the beat of the tempo or the entry of a section of the orchestra.

ictus

ictus, stroke

a blow, stroke, stab, thrust, bite, sting

a striking, playing on the lyre

the stroke of a wing

a stroke of lightning, lightning

a beating time, a beat

a beat of the pulse

an attack, shot

hit, struck, blown

stabbed, stung

ictus

ictus

ictus

stroke, ictus

Source: wiktionary.org