since 
(sĭns)
(sĭns)adv.
1. From then until now or between then and now: They left town and haven't been here since.
2. Before now; ago: a name long since forgotten.
3. After some point in the past; at a subsequent time: My friend has since married and moved to California.
prep.
1. Continuously from: They have been friends since childhood.
2. Intermittently from: She's been skiing since childhood.
conj.
1. During the period subsequent to the time when: He hasn't been home since he graduated.
2. Continuously from the time when: They have been friends ever since they were in grade school.
3. Inasmuch as; because: Since you're not interested, I won't tell you about it.
[Middle English sinnes, contraction of sithenes : sithen, since (from Old English siththan : sīth, after + than, variant of thām, dative of thæt, that; see THAT) + -es, adv. suff.; see -S3.]