1. For the reason that; on account of
   "Since it's snowy, let's go skiing";
   - as, because, for, coz [Brit, informal], cos [Brit, informal], cuz [non-standard, informal], forasmuch as [archaic]

1. From that time
   "happy since getting married";
   - as of

1. Happening at a time subsequent to a reference time
   "I haven't seen him since";
   - subsequently, later, afterwards, afterward, after, later on
    
2. In the past
   "long since";
   - ago

Encyclopedia: Since, Colombia