Tractrix
Pronunciation : Tract"rix
Part of Speech : n.
Etymology : [NL. See Tractor.] (Geom.)
Definition : Defn: 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.
Source : Webster's Unabridged Dictionary, 1913