plural of inverse cosine

(mathematics) The trigonometric function 1 − cos(x)

a Fourier series consisting solely of cosine functions

(optics) A law stating that the radiant intensity or luminous intensity observed from an ideal diffusely reflecting surface or ideal diffuse radiator is directly proportional to the cosine of the angle between the direction of the incident light and the surface normal.

(chiefly British spelling) The state or quality of being cosy.

plural of cosiness