noun (plural arses /-ˌsēz/)Prosody
- the unstressed syllable of a metrical foot. The opposite of thesis (sense 3). To the Greeks, the two terms designated the raising and lowering of the foot in walking, but their meanings became reversed in the Latin tradition, where grammarians identified them with the lowering and raising of the voice.
late Middle English: via late Latin from Greek, literally 'lifting', from airein 'raise'