since

Since is a versatile English word that serves as a temporal marker and a causal conjunction. It can express the starting point of an action in time, as in I have lived here since 1990, or introduce a reason, as in Since you asked, I will explain. In some uses it also functions as a preposition before a time expression, for example since Friday.

Etymology and development: Since originates from Old English sidan/síðan meaning “afterward” or “from that time.” It shares a common Germanic root with cognates in related languages such as German seit and Dutch sinds. Over the Middle English and early modern periods, its senses broadened to include the causal meaning “because.”

Temporal usage: The time sense typically combines with perfect tenses (present perfect or past perfect) to indicate a point from which something has continued: I have lived here since 1990; They had known her since childhood. Since answers the question “from when?” and is commonly contrasted with for, which marks duration rather than starting point.

Causal usage and style: The causal sense means “because” and is widely used in both speech and writing. In formal contexts, since can sound slightly more tentative than because, especially when the reason is presented as a premise. When clarity is needed, many writers prefer because to avoid potential ambiguity.

Overall, since is a common, flexible word in English, used to encode starting points in time and to introduce reasons. Its correct use often depends on selecting the appropriate sense for the intended meaning and on the surrounding tense.