whereby

Whereby is a conjunction used in English to indicate the means, method, or instrument by which something occurs or is achieved. In formal writing it introduces a clause that explains how a result is obtained or how an arrangement operates. It is commonly found in legal, contractual, and administrative text, where it helps to connect a stated mechanism or agreement with its effect. Examples include: “The parties signed a treaty whereby all trade barriers would be removed” and “The city uses a system whereby residents can submit requests online.”

Etymology-wise, whereby derives from where + by, and has a long history in English. It is a relatively formal or sometimes archaic word in everyday speech, with more common substitutes such as by which, through which, or in which. It is distinct from wherein, which typically refers to a location or condition, whereas whereby emphasizes the method or means by which something happens. In usage, whereby often introduces the instrumentality of a process rather than a physical place, and it is typically encountered in written documents and formal discourse.