middle pillar; central pillar
Refers to a pillar located in the middle of a structure, often in traditional Japanese architecture or framing.
この古い家は中柱がしっかりしている。
This old house has a sturdy central pillar.
Compound of 中 (naka, 'middle') and 柱 (hashira, 'pillar'). The reading なかばしら is a straightforward combination.