Definition of: since

(sins) adverb
1. From a past time, mentioned or referred to, up to the present.
2. At some time between a certain past time or event and the present: He was willing at first, but has since refused.
3. In time before the present; ago; before now.
—prep.
1. During or within the time after or later than: Things have changed since you left.
2. Continuously throughout the time after: He has been working since noon.
—conj.
1. During or within the time after which.
2. Continuously from the time when: She has been ill since she arrived.
3. Because of or following upon the fact that; inasmuch as. See synonyms under BECAUSE. [ME sithens <OE siththan afterwards + -s (adverbial termination)]