The cotangent is a trigonometric function defined as the ratio of the adjacent side to the opposite side in a right triangle. It is often abbreviated as cot and is the reciprocal of the tangent function. In mathematical terms, if θ is an angle in a right triangle, then cot(θ) = adjacent/opposite. In the context of the unit circle, the cotangent of an angle can also be expressed as the x-coordinate divided by the y-coordinate of a point on the circle. This function is periodic, with a period of π, meaning that cot(θ + π) = cot(θ) for any angle θ.