since

Etymology

From Middle English syns, synnes, contraction of earlier sithens, sithence, from sithen (“after, since”) ( + -s, adverbial genitive suffix), from Old English sīþþan, from the phrase sīþ þǣm (“after/since that (time)”), from sīþ (“since, after”) + þǣm dative singular of þæt. Cognate with Dutch sinds (“since”), German seit (“since”), Danish siden (“since”), Icelandic síðan (“since”) Scots syne (“since”).

adv

1. From a specified time in the past.
   I met him last year, but haven't seen him since.
   A short/long time since

prep

1. From: referring to a period of time ending in the present and defining it by the point in time at which it started, or the period in which its starting point occurred.
   1. Continuously during that period of time.
      I have known her since last year.
      Since the mid-1980s, when Indonesia first began to clear its bountiful forests on an industrial scale in favour of lucrative palm-oil plantations, “haze” has become an almost annual occurrence in South-East Asia. 2013-06-29, “Unspontaneous combustion”, in The Economist, volume 407, number 8842, page 29
      Since the 1980s, computers have had increasing roles in all aspects of human life—including an involvement in criminal acts. 2013 September-October, Simson Garfinkel, “Digital Forensics”, in American Scientist
   2. At certain points during that period of time.
      "Mujtahidd" has attracted almost 300,000 followers since the end of last year, when he began posting scandalous claims about the Saudi elite. April 19, 2012, Josh Halliday, “Free speech haven or lawless cesspool – can the internet be civilised?”, in the Guardian

conj

1. From the time that.
   I have loved you since I first met you.
   He had one hand on the bounce bottle—and he'd never let go of that since he got back to the table—but he had a handkerchief in the other and was swabbing his deadlights with it. 1913, Joseph C. Lincoln, Mr. Pratt's Patients, chapter 6
2. Because.
   Since you didn't call, we left without you.
   Since disbursement is the last step in the process of creating a mortgage instrument, the disbursement date may lag the transaction date by a considerable period. 1970, Jack M. Guttentag, “New Series on Home Mortgage Yields Since 1951, Volume 92”, in National Bureau of Economic Research, page 132
3. (obsolete) When or that.