one-way

The word "one-way" is a compound formed by combining "one" (from Old English "ān," meaning "single" or "alone") and "way" (from Old English "weg," meaning "path" or "direction"). The term emerged in the early 19th century, initially describing roads or routes permitting travel in a single direction. Over time, it expanded metaphorically to describe communication systems (e.g., "one-way mirror") or rigid systems lacking reciprocity. The logic is straightforward: "one" restricts the scope, while "way" defines the medium of movement or interaction.