So tomorrow's happening is a "tangent." Math definition? Or something completely unrelated definition.
Geometry - (1) touching at a single point, as a tangent in relation to a curve or surface. (2) in contact along a single line or element, as a plane with a cylinder.
tangential (def 3) - a line or a plane that touches a curve or a surface at a point so that it is closer to the curve in the vicinity of the point than any other line or plane drawn through the point.
Trigonometry - (in a right triangle) the ratio of the side opposite a given angle to the side adjacent to the angle.
Other - a completely different line of thought or action.