\Ar"sis\ ([aum]r"s[i^]s), n. [L. arsis, Gr. 'a`rsis a
raising or lifting, an elevation of the voice, fr. a'i`rein
to raise or lift up. Its ordinary use is the result of am
early misapprehension; originally and properly it denotes the
lifting of the hand in beating time, and hence the unaccented
part of the rhythm.]
1. (Pros.)
   (a) 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. --Hermann.
   (b) That elevation of voice now called {metrical
       accentuation}, or the rhythmic accent.
Note: It is uncertain whether the arsis originally consisted
      in a higher musical tone, greater volume, or longer
      duration of sound, or in all combined.
2. (Mus.) 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}.
   --Moore.