D defs.my
Entry 1 sense Webster, 1913

Tractrix

· Tract·rix · IPA
01 n. A curve such that the part of the tangent between the point of tangency and a given straight line is constant; -- so called because it was …
  1. 1.
    A curve such that the part of the tangent between the point of tangency and a given straight line is constant; -- so called because it was conceived as described by the motion of one end of a tangent line as the other end was drawn along the given line.(Geom.)