n (figuratively) An important moment when a decision is made that will determine future events.
n (geometry) 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.
n (architecture) A point made by the intersection of two curved lines or curved structures. A common motif in Gothic architecture.Russell Sturgis, ed. (1902). A Dictionary of Architecture and Building: Biographical, Historical, and Descriptive. 3. Macmillan.