Definition of secant
1
: a straight line cutting a curve at two or more points
2
: a straight line drawn from the center of a circle through one end of a circular arc to a tangent drawn from the other end of the arc
3 a
: a trigonometric function that for an acute angle is the ratio of the hypotenuse of a right triangle of which the angle is considered part and the leg adjacent to the angle
b
: a trigonometric function sec θ that is the reciprocal of the cosine for all real numbers θ for which the cosine is not zero and that is exactly equal to the secant of an angle of measure θ in radians
