Since

Since is used to show that something has been true from a particular time in the past up to now, or to give a reason for something. It can also function as a preposition or adverb.

“Since” comes from Middle English “sithen” or “sithence,” meaning afterwards or from that time, built from Old English “sīþ” (after, later) plus “þence” (from then). Over time, the word shortened in both form and meaning. The causal sense (‘because’) developed from the idea that something has been true ever since a certain event.