Nizhyn (nyĭzhˈĭn) [key], Rus. Nezhin, city (1989 pop. 81,000), N Ukraine, on the Oster River. It is a rail terminus on the main Moscow-Kiev line and an agricultural trade center. Industries include engineering, food processing, and the manufacture of machinery and railroad cars. Known in the 11th cent., the city was the center of the Nizhyn Ukrainian Cossack regiment from 1649 to 1782. It became an important trading center in the 17th and 18th cent. after Greek merchants received permission to settle there in 1657.