noun
metropolis; big city
Refers to a very large, bustling city, often with a connotation of modernity and scale. Commonly used for cities like Tokyo, New York, or London.
東京は世界有数の大都会だ。
Tokyo is one of the world's great metropolises.
彼は田舎から大都会へ引っ越した。
He moved from the countryside to the big city.
都市 is a more formal or technical term for 'city', often used in contexts like urban planning. 大都会 is more expressive and emphasizes the grand scale.
Compound of 大 (だい, 'big') + 都会 (とかい, 'city'). The reading is on'yomi, and the word is a straightforward Sino-Japanese formation.