a hand railing attached to a wall

(idiomatic) A quiet, non-participating, or unseen observer; an eavesdropper or witness.

(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.

(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.

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

A brick wall, having enclosed flues connected to a fire, to which fruit trees are attached in order to hasten growth and ripening

Used other than figuratively or idiomatically: see brick, wall. A wall made of bricks. / (figuratively) An obstacle. / (sound engineering) A type of anti-aliasing filter with a steep cutoff.

To build a brick wall around. / (sound engineering) To filter using a brick wall filter. / To halt or limit abruptly. / To be uncooperative and unresponsive.

Alternative spelling of seawall

Any of several structures used to restrain a vertical-faced mass of earth.