a. [ L. tangens, -entis, p. pr. ] Touching; touching at a single point; specifically (Geom.) meeting a curve or surface at a point and having at that point the same direction as the curve or surface; -- said of a straight line, curve, or surface; as, a line tangent to a curve; a curve tangent to a surface; tangent surfaces. [ 1913 Webster ]

Tangent plane (Geom.), a plane which touches a surface in a point or line. --
Tangent scale (Gun.), a kind of breech sight for a cannon. --
Tangent screw (Mach.), an endless screw; a worm. [ 1913 Webster ]

[ 1913 Webster ]

n. [ L. tangens, -entis, p. pr. of tangere to touch; akin to Gr. &unr_; having seized: cf. F. tangente. Cf. Attain, Contaminate, Contingent, Entire, Tact, Taste, Tax, v. t. ] (Geom.) A tangent line curve, or surface; specifically, that portion of the straight line tangent to a curve that is between the point of tangency and a given line, the given line being, for example, the axis of abscissas, or a radius of a circle produced. See Trigonometrical function, under Function. [ 1913 Webster ]

Artificial tangent, or
Logarithmic tangent, the logarithm of the natural tangent of an arc. --
Natural tangent, a decimal expressing the length of the tangent of an arc, the radius being reckoned unity. --
Tangent galvanometer (Elec.), a form of galvanometer having a circular coil and a short needle, in which the tangent of the angle of deflection of the needle is proportional to the strength of the current. --
Tangent of an angle, the natural tangent of the arc subtending or measuring the angle. --
Tangent of an arc, a right line, as ta, touching the arc of a circle at one extremity a, and terminated by a line ct, passing from the center through the other extremity o. [ 1913 Webster ]

a. (Geom.) Tangential. [ 1913 Webster ]

a. (Geom.) Of or pertaining to a tangent; in the direction of a tangent. [ 1913 Webster ]

Tangential force (Mech.), a force which acts on a moving body in the direction of a tangent to the path of the body, its effect being to increase or diminish the velocity; -- distinguished from a normal force, which acts at right angles to the tangent and changes the direction of the motion without changing the velocity. --
Tangential stress. (Engin.) See Shear, n., 3. [ 1913 Webster ]

adv. In the direction of a tangent. [ 1913 Webster ]

. A tension spoke of a bicycle or similar wheel, secured tangentially to the hub. [ Webster 1913 Suppl. ]

. (a) A worm or worm wheel; a tangent screw. (b) A wheel with tangent spokes. [ Webster 1913 Suppl. ]