What is the meaning of Arsis?

The stronger part of a musical measure: the part containing the beat.

The stronger part of a metrical foot: the part containing the long (heavy) syllable in quantitative meter, or the stressed syllable in a qualitative meter.

The elevation of the hand, or that part of the bar at which it is raised, in beating time; the weak or unaccented part of the bar, opposed to the thesis.

The elevation of the voice to a higher pitch in speaking.

arsis

dative/ablative masculine/feminine/neuter plural of arsus

Source: wiktionary.org