log; unsawn timber
Refers to a whole, unsawn log, often used in contexts like log houses or log bridges.
丸木を川に流して運んだ。
They floated logs down the river to transport them.
この橋
This bridge is made of logs.
log bridge
dugout canoe
Compound of 丸 (まる, 'round') and 木 (き, 'tree, wood'), literally 'round wood'.