<p><strong>Noun</strong></p><ul><li>(in a right triangle) the ratio of the side opposite a given angle to the side adjacent to the angle.</li><li>Also called tan.</li><li>(of an angle) a trigonometric function equal to the ratio of the ordinate of the end point of the arc to the abscissa of this end point, the origin being at the center of the circle on which the arc lies and the initial point of the arc being on the x-axis.</li><li>tg, tgn.</li></ul>