girder; girt
A horizontal structural beam in traditional Japanese wooden architecture, often connecting pillars. The term is technical and primarily used in architectural or historical contexts.
In this old folk house, the girt connects pillar to pillar.
Compound of 胴 (dō, 'trunk, torso') and 差し (sashi, from 差す, 'to insert, to place across'). The name likely refers to a beam placed at about the height of a person's torso in a wooden structure.