breastwork; parapet (military)
Military fortification term: a low defensive wall or earthwork, often temporary, used to protect soldiers.
See also: 胸墻
The soldiers took cover behind the breastwork.
Rare, literary use for a fortified place or stronghold; not a common standalone word for fortress in modern Japanese.
The old castle was known as an impregnable fortress.
Architectural term for a low protective wall at the edge of a roof, balcony, bridge, or terrace.
See also: パラペット
I looked down at the city from the parapet on the rooftop.
chest wall
Medical/anatomical term for the thoracic wall; used in clinical contexts.
The chest wall surgery was performed by a specialist.
thoracic wall muscles; muscles of the chest wall
Compound of 胸 (chest, breast) and 壁 (wall). The military and architectural meanings are calques from Western terms; the anatomical sense is a direct extension of the kanji meanings.