A "cusp" refers to a point of transition between two different states or conditions. In various fields, it can signify a boundary or edge where one thing changes into another. For example, in astrology, a cusp is the dividing line between two zodiac signs, indicating that a person born on this line may exhibit traits from both signs, such as Aries and Taurus. In mathematics, a cusp can describe a specific point on a curve where the curve changes direction sharply. This is often seen in graphs of functions, where the cusp represents a point of non-differentiability. Understanding cusps is important in both astrology and mathematics for interpreting changes and characteristics.