unidirectional

This term is primarily used in technical, scientific, and regulatory contexts to describe a strict one-way constraint. It carries a clinical or precise tone, making it more appropriate for engineering manuals, medical descriptions, or traffic laws than for casual conversation, where "one-way" is the standard preference.

In physics and electronics, the word emphasizes a functional limitation or a design feature that prevents backflow or reverse polarity. It describes a system where the path of movement is absolute and irreversible, contrasting with bidirectional systems that allow two-way traffic or exchange.