The fifth in descent from Cain. He was the first to violate the primeval ordinance of marriage (Genesis 4:18-24). His address to his two wives, Adah and Zillah (4:23,24), is the only extant example of antediluvian poetry. It has been called "Lamech's sword-song." He was "rude and ruffianly," fearing neither God nor man. With him the curtain falls on the race of Cain. We know nothing of his descendants.
The seventh in descent from Seth, being the only son of Methuselah. Noah was the oldest of his several sons (Genesis 5:25-31; Luke 3:36).
These dictionary topics are from M.G. Easton M.A., D.D., Illustrated Bible Dictionary, Third Edition, published by Thomas Nelson, 1897. Public Domain, copy freely.
Easton, Matthew George. "Entry for 'Lamech'". "Easton's Bible Dictionary". <http://classic.studylight.org/dic/ebd/view.cgi?number=T2233>. 1897.