Square or rectangular shaped serif at right angles to the character’s main stem and often of the same thickness. Slab serifs are a hallmark of Egyptienne typefaces.

In typography, a slab serif (also called mechanistic, square serif or egyptian) typeface is a type of serif typeface characterized by thick, block-like serifs. Slab serif typefaces generally have no bracket (feature connecting the strokes to the serifs). Because of their bold appearance, they are most commonly used in large headlines and advertisements but are seldom used in body text.