: the lighter or shorter part of a poetic foot especially in quantitative verse
b
: the accented or longer part of a poetic foot especially in accentual verse
2
: the unaccented part of a musical measure compare thesis
Word History
Etymology
Middle English, "raising of the voice," borrowed from Latin, "raising of the voice on an emphatic syllable," borrowed from Greek ársis "lifting, raising, raising of the foot to mark an unstressed beat (in music and prosody, opposed to thésisthesis), from ar- (contracted from *awer-), base of aeírein "to lift, raise" (also, "to join, attach, harness") + -sis-sis — more at aorta