(idiomatic, UK, Ireland, regarding a workplace, etc.) Very busy, swamped.

(idiomatic) crazy, mad

(civil engineering) A structure inserted in the ground and used to maintain an excavation open or to isolate portions of contaminated ground. It can be built of any material from steel to reinforced concrete.

plural of diaphragm wall

(physics) The energy per unit area of the boundary between adjoining ferromagnetic domains in a solid

(performing arts, idiomatic) The imaginary invisible wall at the front of the stage in a proscenium theatre, through which the audience sees the action in the world of the play.

(cytology) A thick, fairly rigid, layer formed around individual cells of bacteria, Archaea, fungi, plants, and algae (but not animals and other protists which generally have cell membranes without cell walls). The cell wall is external to the cell membrane and serves a structural function helping the cell maintain its shape and protecting the cell from damage.

A street in Manhattan, New York City, New York, United States, where the palisade of New Amsterdam was once located.

A clock mounted on a wall.

(idiomatic) Wildly unconventional; bizarre; absurd. / (idiomatic) Of a person's behaviour: greatly inappropriate.