The word 基于 is formed by combining the character 基, meaning "foundation" or "base", with the character 于, a classical grammatical particle meaning "at", "on", or "in". This fusion creates a new conceptual unit where the concrete idea of a "foundation" is placed into a relational framework by 于, together expressing the abstract notion of "resting upon" or "based on". It is a direct, logical marriage of a substantive noun with a relational preposition to form a single prepositional concept.