[an.a.cru.sis] n, pl -cru.ses [NL, fr. Gk anakrousis beginning of a song, fr. anakrouein to begin a song, fr. ana- + krouein to strike, beat; akin to Lith krausyti to strike] (1830) 1: one or more syllables at the beginning of a line of poetry that are regarded as preliminary to and not a part of the metrical pattern
2: upbeat; specif: one or more notes or tones preceding the first downbeat of a musical phrase