The objects of mathematics can have fascinating names. Mathematical words describe numbers, shapes, and logical concepts. Some are ordinary words adapted for a specific purpose, such as cardinal, cube, group, face, field, ring, and tree. Others are unusual, like cosecant, holomorphism, octodecillion, polyhedron, and pseudoprime. Some sound peculiar—deleted comb space, harmonicmap, supremum norm, twisted sphere bundle, to name a few. Mathematical words have appeared in poems (see [19]). Let us look at some mathematical words.

Consider the*lemniscate*, a curve shaped like a figure-eight¹ as shown in Figure 1.1. We learn in [46] that it gets its name from