noun
log bridge; single-log bridge
A bridge made from a single log or narrow plank, often found in rural or traditional settings.
山奥の渓谷に一本橋がかかっていた。
A log bridge spanned the mountain valley.
Compound of 一本 (ippon, 'one long slender object') + 橋 (hashi, 'bridge'), referring to a bridge made from a single log.