The word 最先 is formed by combining two independent characters, each contributing its core meaning to create a new, composite idea. The first character, 最 (zuì), carries the fundamental sense of "utmost" or "to the highest degree", acting as a superlative marker. It is placed before the second character, 先 (xiān), which embodies the core concept of "early", "first", or "before". Their combination is purely semantic, where 最 intensifies 先, resulting in the integrated meaning of "the very first" or "the earliest in sequence". It is a direct structural pairing of modifier and root, forming a single conceptual unit.