The word 市区 is formed by combining two meaningful characters: 市, which means "city" or "market", and 区, which means "area" or "district". It is not a random pairing but a logical, conceptual compound where the first element defines the type and the second defines its spatial or administrative nature. By fusing these core ideas, the term naturally conveys the specific concept of the "urban area" or "city proper", the central, built-up part of a city, distinct from its suburbs or surrounding countryside.