壁

铜墙铁壁

tóng qiáng tiě bì

copper wall, iron bastion (idiom); impenetrable defense

凿壁偷光

záo bì tōu guāng

lit. to pierce the wall to steal a light (idiom)

间壁

jiàn bì

next door

关税壁垒

guān shuì bì lěi

tariff wall

陡壁

dǒu bì

steep cliff

隔壁

gé bì

next door

隔壁有耳

gé bì yǒu ěr

walls have ears

隔壁老王

gé bì lǎo wáng

Mr Wang from next door (term used jocularly to refer to a neighbor who is supposedly sleeping with one's wife)

隔壁邻居

gé bì lín jū

next-door neighbor

障壁

zhàng bì

barrier

颓垣断壁

tuí yuán duàn bì

lit. walls reduced to rubble (idiom)

飞檐走壁

fēi yán zǒu bì

to leap onto roofs and vault over walls (usually associated with martial arts)