Foreign object damage

Foreign object debris (FOD) is a substance, debris or article alien to a vehicle or system which would potentially cause damage, particularly in an aerospace setting.

Foreign object damage is any damage attributed to a foreign object (i.e. any object that is not part of the vehicle) that can be expressed in physical or economic terms and may or may not degrade the product's required safety or performance characteristics. FOD is an acronym often used in aviation to describe both the damage done to aircraft by foreign objects, and the foreign objects themselves.