From Longman Dictionary of Contemporary Englishtangenttan‧gent /ˈtændʒənt/ noun [countable] 1 → go off at a tangent2 technicalHM a straight line that touches the outside of a curve but does not cut across it
Examples from the Corpus
tangent• Never quite abstract, never entirely candid, always at a tangent to the world, Hodgkin is a strangely opaque painter.• After all, tangents are extremely valuable for your writing.• Within the box it is possible to describe slopes and turns as numerical ratios, as tangents.• As for going off at tangents, my dear, I do it myself, hormone balance not withstanding.• All along the way, short tangents beckoned.Origin tangent (1500-1600) Latin present participle of tangere; → TANGIBLE 