ridge of a roof
Refers to the highest horizontal line where two roof slopes meet. Also appears as the prefix むな in compounds like 棟木 (むなぎ, ridgepole).
The ridge of the roof was damaged by the typhoon.
back of a sword
The blunt back edge of a single-edged blade, opposite the cutting edge. Often contrasted with 刃 (は, blade).
See also: 刀背
He struck the opponent's arm with the back of the sword.
counter for buildings
Used to count houses, apartment buildings, and other structures. Attaches directly to numbers.
There are three large apartment buildings in this town.
The swordsman struck his opponent with the back of his blade.
Three new apartment buildings were built in this area.
刀背 is a more formal, technical term for the back of a sword blade, while 棟 is the everyday word for the same part.
軒 is the everyday counter for houses and small shops, while 棟 is used for larger or more formal buildings like apartment blocks.
棟 is another homophone of 旨, but it refers to a building or the ridge of a roof, unrelated to 旨's meaning of 'gist' or 'instructions'.
separate building; outbuilding; outhouse
one building; the same building
main ridge of a roof; top ridge
hip (of roof)
hipped roof; hip roof
The kanji 棟 combines 木 (tree/wood) and 東 (east), originally referring to the main ridgepole of a building. The reading むね is native Japanese and also appears in related words like 胸 (chest), suggesting a core or central line.