The word 高速 is formed by combining two independent characters, each with its own core meaning: 高 (gāo), meaning "high" or "tall", and 速 (sù), meaning "speed" or "fast". They are joined in a straightforward, descriptive manner where "高" modifies "速", conceptually fusing to create the single, unified idea of "high speed". This directly reflects the compound's primary meaning, most commonly understood as "highway" (a road for high-speed travel), showcasing how Chinese frequently forms new concepts by logically connecting fundamental pictographic or ideographic characters.