since

From a specified time in the past.

I met him last year, but haven't seen him since.

A short/long time since

From: referring to a period of time ending in the present and defining it by the point in time at which it started, or the period in which its starting point occurred. Continuously during that period of time.

I'd known her only since the previous year, so from/since the moment we got married we’ve quarrelled.

I'd been working since six o’clock, and I was getting tired.

Since the mid-1980s, when Indonesia first began to clear its bountiful forests on an industrial scale in favour of lucrative palm-oil plantations, “haze” has become an almost annual occurrence in South-East Asia.

Since the 1980s, computers have had increasing roles in all aspects of human life—including an involvement in criminal acts.

From: referring to a period of time ending in the present and defining it by the point in time at which it started, or the period in which its starting point occurred. At certain points during that period of time.

"Mujtahidd" has attracted almost 300,000 followers since the end of last year, when he began posting scandalous claims about the Saudi elite.

From the time that.

I have loved you since I first met you.

I've known her since I've lived in her street, but I've not seen her out of the house since her husband died.

Since leaving school, I've completely changed.

He had one hand on the bounce bottle—and he'd never let go of that since he got back to the table—but he had a handkerchief in the other and was swabbing his deadlights with it.

Because.

Since you didn't call, we left without you.

The story struck the depressingly familiar note with which true stories ring in the tried ears of experienced policemen.[…]The second note, the high alarum, not so familiar and always important since it indicates the paramount sin in Man's private calendar, took most of them by surprise although they had been well prepared.

Since disbursement is the last step in the process of creating a mortgage instrument, the disbursement date may lag the transaction date by a considerable period.

obsoleteWhen or that.

O ſir Iohn, doe you remember ſince wee lay all night in the Winde-mill, in S Georges field.