osculating circle

noun

: a circle which is tangent to a curve at a given point, which lies in the limiting plane determined by the tangent to the curve and a point moving along the curve to the point of tangency, which has its center situated on the normal to the curve at the given point and, also, on the concave side of the projection of the curve onto the limiting plane, and which has a radius equal to the radius of curvature

Word History

First Known Use

1816, in the meaning defined above

The Ultimate Dictionary Awaits

Expand your vocabulary and dive deeper into language with Merriam-Webster Unabridged.

1. Expanded definitions
2. Detailed etymologies
3. Advanced search tools
4. All ad-free

Discover what makes Merriam-Webster Unabridged the essential choice for true word lovers.

Start Your Free Trial Now