(theater) The division between the fictional world depicted, and the actual actors, props, etc. / (art) The divide between critics or audience members and author or theater practitioner.

(computing) The actual time of day, as would be seen on a wall clock; contrasted with the (possibly inaccurate) time according to a computer system.

plural of tieback wall

plural of writing on the wall

plural of ledger wall

(mining) The wall under a vein; the footwall.

(usually in the plural) A wall around a city, built to define the city's boundaries, and sometimes to protect it from aggressors.

A green wall, a wall covered by greenery.

plural of Néel wall

plural of Bloch wall