syllable (n.)

1560s, in mathematics, from Greek lemma (plural lemmata) "something received or taken; an argument; something taken for granted," from root of lambanein "to take," from PIE root *(s)lagw- "to seize, take" (source also of Sanskrit labhate, rabhate "seizes;" Old English læccan "to seize, grasp;" Greek lazomai "I take, grasp;" Old Church Slavonic leca "to catch, snare;" Lithuanian lobis "possession, riches"). Related: Lemmatical.

"containing or consisting of seven syllables," 1735, from Late Latin heptasyllabus, from Greek heptasyllabos "of seven syllables," from hepta (see seven) + syllabē "syllable" (see syllable). The noun heptasyllable "line of seven syllables" is attested by 1757. A favorite measure of the 17th century poets. In alternation with eights, it might be regarded as a catalectic octosyllable.