This page is about machine loads. For the epidemiological meaning, see Parasite load.
Parasitic load or parasitic loss may refer to
in internal combustion engines, it refers to devices that take energy from the engine in order to enhance the engine's ability to create more energy or convert energy to motion.
in electricity production, it is any of the loads or devices powered by the generator, not contributing to net electric yield
With regard to railway locomotives, it is any of the loads or devices powered by the prime mover not contributing to tractive effort (such as an air compressor, traction motor blower, or radiator fans).