RLU

RLU may refer to:
 * Rectified linear unit, a neuron activation function used in neural networks, usually referred to as an ReLU
 * Relative light unit, a unit for measuring cleanliness by measuring the levels of Adenosine Triphosphate
 * Remote line unit, a type of switch in the GTD-5 EAX switching system
 * RLU-1 Breezy, an American homebuilt aircraft design
 * Rusline, a Russian airline whose ICAO airline code is RLU