The word 正常 is formed by combining two independent characters, each contributing a core meaning that merges to create a new, unified concept. The first character, 正, carries the idea of being "correct", "proper", or "upright". The second character, 常, means "constant", "regular", or "usual". When placed together, their meanings fuse to express the state of something being "as it properly and regularly should be", hence, the combined meaning of normal, proper, or regular. It is a conceptual compound where the whole meaning is derived from the logical intersection of its parts.