from Wiktionary, Creative Commons Attribution/Share-Alike License
- n. A point on a curve at which there are two tangents (because it touches itself, or has a cusp)
from the GNU version of the Collaborative International Dictionary of English
- adj. a point of a curve at which two branches cross each other. Conjugate or isolated points of a curve are called double points, since they possess most of the properties of double points (see Conjugate). They are also called acnodes, and those points where the branches of the curve really cross are called crunodes. The extremity of a cusp is also a double point.
Sorry, no etymologies found.