1) Obsolete forms of ‘since’.
1487 with ... repentance of all my synnes that ever I did sith the first houre I was born, Hull
1515 if eny suche lees were made, where it was made and what tyme and how long sithen, Gleadless
1525 dymysed the premysses to the said defendaunt [who] peasibly manured and occupied the same euersythen until this day, Leeds
1583 sythence the same purchase have barganed and sould ... one messuage, Meltham
1607 about xxiiij yeares sithence, Salton.