The word 大街 is formed by directly combining two independent characters, each carrying its own core meaning: 大 (dà), meaning "big" or "large", and 街 (jiē), meaning "street". Their union is not grammatical but conceptual, creating a composite idea where the attribute "big" modifies the noun "street" to produce the straightforward and literal concept of a "main street" or "boulevard", essentially a major public thoroughfare. It is a simple, descriptive compound where the whole meaning is transparently the sum of its visible parts.