Refers specifically to the central wooden pillar that runs through the core of a traditional Japanese pagoda, providing structural stability. Often discussed in architectural or historical contexts.
See also: 心柱 (しんばしら)
The five-story pagoda at Horyu-ji has a central pillar running through it.
Compound of 心 (しん, 'heart, center') + の (possessive particle) + 柱 (はしら, 'pillar'). The reading しんのはしら is a literal rendering of the kanji, while the more common 心柱 (しんばしら) uses a contracted reading.