The portion of a brick cut across the width, is called

In the context of brick masonry and building construction, a "bat" refers to a portion of a brick that is cut across the width to fit within the brickwork. Bats are commonly used to ensure that bricks fit properly into a pattern or layout, especially at the ends or edges of a wall. Bats can be cut in various ways to achieve the desired dimensions.

The other options are:
Option A: Closer - A closer is a brick that is cut along its length to fit within the brickwork, typically at the end of a wall to maintain the bond.
Option B: Half brick - A half brick is simply a whole brick that has been divided into two equal parts along its length.
Option C: Bed - The bed is a term that typically refers to the horizontal surface of a brick or the surface on which it rests in a wall.

So, the correct answer is Option D: Bat, which specifically refers to a portion of a brick cut across its width to fit into masonry work.