ARSIS

noun that elevation of voice now called metrical accentuation, or the rhythmic accent.

2. arsis ·noun that part of a foot where the ictus is put, or which is distinguished from the rest (known as the thesis) of the foot by a greater stress of voice.

3. arsis ·noun 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 thesis.