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.
4. Continuously from:
They have been friends since childhood.
5. Intermittently from:
She's been skiing since childhood.
6. During the period subsequent to the time when:
He hasn't been home since he graduated.
7. Continuously from the time when:
They have been friends ever since they were in grade school.
8. Inasmuch as; because:
Since you're not interested, I won't tell you about it.
9. Middle English sinnes
10. contraction of sithenes