Spontaneous nipple discharge is when fluid comes out of the nipple on its own. This means a person has not squeezed or pressed on a nipple or breast to force out the fluid.
Spontaneous nipple discharge is often noticed as a stain on a bra or clothing. Sometimes a person can see this discharge after taking a shower.
Fluid that comes out only when the nipple or breast is squeezed or pressed is different from a spontaneous discharge.
WebMD Medical Reference from Healthwise