/ˈtændʒənt/
tan·gent
BrE /ˈtændʒənt/
NAmE /ˈtændʒənt/
(geometry)
a straight line that touches the outside of a curve but does not cross it
(abbreviation tan) (mathematics)
the ratio of the length of the side opposite an angle in a right-angled triangle to the length of the side next to it
➡ compare cosine, sine
fly/go off at a ˈtangent(BrE) (NAmE go off on a ˈtangent)
(informal)
to suddenly start saying or doing sth that does not seem to be connected to what has gone before