An air outlet nozzle of a heating and/or air-conditioning system of a vehicle is provided. It has a displacer which is connected to a nozzle mouth element mounted displaceably in the nozzle housing. In order, with as little structural space as possible and as little flow losses as possible, to be able to control the diffusivity of the air jet emerging from the air outlet nozzle, the flow resistance and the axial position of the displacer can be adjusted.