nonconforming use

Also known as a prior nonconforming use (PNU), this exists when a zoning code is changed, but a parcel of land that is already being used for something disallowed by the new zoning code is "grandfathered in" (is allowed to continue).  For example, if a neigborhood zoning is changed to residential, a corner grocery store may be allowed to continue to operate.  The PNU will generally end when the use of the land is changed (so if the grocery store closes, the new zoning code will bar a new store from moving in).