1520s, "contraction of a word by omission of middle sounds or letters," from Latin syncope "contraction of a word by elision," from Greek synkope "contraction of a word," originally "a cutting off, cutting up, cutting short," from synkoptein "to cut up," from syn- "together, thoroughly" (see syn-) + koptein "to cut," which is perhaps from PIE root *kop- "to beat, strike, smite" (see hatchet (n.)).
An earlier use of the word in pathology is represented by Middle English syncopis, sincopin "loss of consciousness accompanied by weak pulse" (c. 1400, from Late Latin accusative syncopen); compare Old French syncope "illness, fainting fit" ("failure of the heart's action," hence "unconsciousness"). The spelling of this was re-Latinized 16c. Related: Syncopic; syncoptic.