bitangential
/ˌbaɪ.tænˈdʒɛnʃəl/; /baɪ.tænˈdʒɛnʃuəl/Definitions
1. adjective
Extending or lying between two tangents or tangent lines.
“The bitangential lines intersected at the center of the circle.”
2. noun
A line or curve that is bitangential to a curve or surface.
“The bitangential points of the curve are of great interest in mathematics.”