horizein

Horizein is a classical Greek verb (from the root ὁρίς/ὁρίζω) meaning to bound, delimit, or define; to determine the scope or limits of something, or to set terms or conditions. The word is related to the noun horos, meaning boundary, and to the idea that a horizon marks a bounding line. The related noun horismos or horismós is often rendered as “definition” or “designation” in philosophical contexts. This linguistic family underpins the modern English word horizon, which carries the sense of a spatial or conceptual boundary.

In ancient Greek philosophy and rhetoric, horizein denotes the act of defining or delimiting a term or concept. It is used to describe the process of setting out the scope of a discourse, the content of a definition, or the essential attributes that distinguish a thing from others. Philosophers employed the verb to indicate how terms are bounded, how meanings are fixed, and how distinctions are made within argumentative or classificatory work. The emphasis is on establishing precise limits and clear terms for discussion.

Today, horizein is primarily encountered in philological, textual, and historical study of Greek philosophy and language. It is invoked in analyses of how ancient authors approached definition, classification, and the articulation of meaning. While not a common term in everyday modern Greek, it remains a useful analytic reference for understanding historical discussions of delimitation and definition in classical philosophical writings.