What does tangency mean?
Tangency is a noun meaning the condition of touching at a particular point without crossing there. It is used especially in geometry, where it describes the relationship between a curve or surface and another curve, surface, or line that touches it. The place where this contact occurs is called the point of tangency, and a line with this relationship is called a tangent. The word is recognized by the suffix “-ency,” but its meaning is highly specific rather than generally suggestive of touch. In broader writing, tangency can occasionally describe a close or exact meeting between two things, such as ideas or circumstances. Because the term has a precise technical history, it is especially useful in discussions of curves, surfaces, calculus, and related geometric relationships.
nounIn geometry, the condition of two curves or surfaces touching at a common point without crossing at that point. The common point is called the point of tangency.
- The geometric condition in which two curves or surfaces touch at a common point without crossing there.
"The circle and the line are in a state of tangency at the point where the line touches the circle."
"The point of tangency lies at the uppermost point of the circle."
"The researchers identified a tangency between the two curves in the experimental data."
The standard plural is “tangencies.”
"The curves have several tangencies within the same region."
Tangency is geometry’s perfect almost-miss: a contact precise enough to be touching, but without a crossing.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Where does tangency come from?
The word comes through Latin, where tangentia referred to touching or contact and was associated with tangent-, a form derived from tangere, meaning “to touch.” English adopted the term in mathematical usage during the early modern period. Its relatives include tangent, tangential, and tangible, all of which ultimately reflect the same Latin root associated with touching.
Related word forms
How tangency is actually used
Tangency is primarily a technical mathematical term. In general contexts, it can also refer to a close or precise meeting of people, ideas, or circumstances, though this figurative use is less common.
Easily confused with tangency
A tangent is the straight line that touches a curve at its point of tangency, whereas tangency is the condition of touching itself.