What is the meaning of Cusp?

A sharp point or pointed end.

An important moment when a decision is made that will determine future events.

A point of a curve where the curve is continuous but has no derivative, but such that it has a derivative at every nearby point.

A point made by the intersection of two curved lines or curved structures, a common motif in Gothic architecture.

A boundary between zodiacal signs and houses.

Any of the pointed parts of a canine tooth or molar.

A flap of a valve of a heart or blood vessel.

A point of transition.

To behave in a reckless or dangerous manner.

Source: wiktionary.org