The Morane-Saulnier L, or Morane-Saulnier Type L, or officially MoS-3, was a French parasol wing one or two-seat scout aeroplane of the First World War. The Type L became one of the first successful fighter aircraft when it was fitted with a single machine gun that fired through the arc of the propeller, which was protected by armoured deflector wedges. Its immediate effectiveness in this role launched an arms race in fighter development, and the Type L was swiftly rendered obsolete. The original Type L used wing warping for lateral control, but a later version designated Type LA was fitted with ailerons.

A monoplane is a fixed-wing aircraft configuration with a single mainplane, in contrast to a biplane or other types of multiplanes, which have multiple planes.