南定（越南语：Nam Định）是越南北部南定省的首府，位于越南首都河内东南90公里。南定市原属越南河南省，1996年该省分成两个小省时改属南定省。

南定是越南陈朝名将陈兴道（Trần Hưng Đạo）的故乡，每年8月18日－20日有纪念其成功击退蒙古军队的节日活动。

Nam Định ( listen) is a city in the Red River Delta of northern Vietnam. It is the capital of Nam Định Province. The city of Nam Định is 90 km south-east of Vietnam's capital, Hanoi. From August 18–20 of each year, there is a festival held in Nam Định called the Co Trach. This celebration honors General Trần Hưng Đạo, a 13th-century national hero who led Vietnamese forces to victory over the invading Mongols. Nam Định is also the birthplace of Letran Student , Dominican Friar and Vietnamese Saint Vicente Liem de la Paz, O.P. in the village of Trà Lũ, De la Paz was canonized by Pope John Paul II on June 19, 1988 and Feast Day on 24 November .