noun
castle tower; donjon
Refers specifically to the central, tallest tower of a Japanese castle. Often used in the compound 天守閣 (てんしゅかく) with the same meaning.
See also: 天守閣 (てんしゅかく)
姫路城の天守は国宝に指定されている。
The castle tower of Himeji Castle is designated a national treasure.
天守から城下町を一望できる。
From the castle tower, you can get a panoramic view of the castle town.
Synonymous compound; 天守閣 is slightly more explicit and commonly used in tourist contexts, while 天守 can sound more technical or historical.
The term 天守 is believed to have originated in the Azuchi-Momoyama period, possibly as a contraction of 天主 (literally 'heavenly lord'), reflecting the tower's symbolic role as the lord's elevated residence. The kanji 天守 ('heavenly protection') later became standard.