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