/ sɪns; NAmE / preposition , conjunction , adverb
■ preposition
1.
(used with the present perfect or past perfect tense) from a time in the past until a later past time, or until now :
She's been off work since Tuesday.
We've lived here since 1994.
I haven't eaten since breakfast.
He's been working in a bank since leaving school.
Since the party she had only spoken to him once.
'They've split up.' ' Since when? '
That was years ago. I've changed jobs since then .
HELP NOTE : Use for , not since , with a period of time:
I've been learning English for five years.
I've been learning English since five years.
2.
since when? used when you are showing that you are angry about sth :
Since when did he ever listen to me?
■ conjunction
1.
(used with the present perfect, past perfect or simple present tense in the main clause) from an event in the past until a later past event, or until now :
Cath hasn't phoned since she went to Berlin.
It was the first time I'd had visitors since I'd moved to London.
It's twenty years since I've seen her.
How long is it since we last went to the theatre?
She had been worrying ever since the letter arrived.
2.
because; as :
We thought that, since we were in the area, we'd stop by and see them.
■ adverb (used with the present, perfect or past perfect tense)
1.
from a time in the past until a later past time, or until now :
He left home two weeks ago and we haven't heard from him since.
The original building has long since (= long before now) been demolished.
2.
at a time after a particular time in the past :
We were divorced two years ago and she has since remarried.
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WORD ORIGIN
late Middle English : contraction of obsolete sithence , or from dialect sin (both from dialect sithen thereupon, afterwards, ever since ).