Webster's Revised Unabridged Dictionary · 1913

Since

Since (sins) , adverb

[For sins, contr. from Old English sithens, sithenes, formed by an adverbial ending (compare Besides) from Old English sithen, also shortened into sithe, sin, Anglo-Saxon sieean, syeean, seoeean, afterward, then, since, after; properly, after that; from sīe after, later, adv. and prep. (originally a comparative adv., akin to Old Saxon sīe afterward, since, Old High German sīd, German seit since, Gothic seiþus late, ni þanaseiþs no longer) + eon instrumental of the demonstrative and article. See That.]

1.
From a definite past time until now; as, he went a month ago, and I have not seen him since.
We since become the slaves to one man's lust. — B. Jonson
2.
In the time past, counting backward from the present; before this or now; ago.
How many ages since has Virgil writ? — Roscommon
About two years since, it so fell out, that he was brought to a great lady's house. — Sir P. Sidney
3.
When or that. [Obsolete]
Do you remember since we lay all night in the windmill in St. George's field? — Shakespeare

Since , preposition

From the time of; in or during the time subsequent to; subsequently to; after; -- usually with a past event or time for the object.
The Lord hath blessed thee, since my coming. — Gen. xxx. 30
I have a model by which he build a nobler poem than any extant since the ancients. — Dryden

Since , conjunction

Seeing that; because; considering; -- formerly followed by that.
Since that my penitence comes after all, Imploring pardon. — Shakespeare
Since truth and constancy are vain, Since neither love, nor sense of pain, Nor force of reason, can persuade, Then let example be obeyed. — Granville