gremlin

A gremlin is a mischievous fictional creature invented at the beginning of the 20th century originally to explain malfunctions in aircraft, and later in other machinery, processes and their operators. Depictions of these creatures vary widely. Stories about them and references to them as the causes of especially inexplicable technical and mental problems of pilots were especially popular during and after World War II.
Use of the term in the sense of a mischievous creature that sabotages aircraft first arose in Royal Air Force (RAF) slang among British pilots stationed in Malta, the Middle East and India in the 1920s, with the earliest printed record in a poem published in the journal Aeroplane in Malta on 10 April 1929. Later sources have sometimes claimed that the concept goes back to World War I, but there is no print evidence of this.
There is evidence of an even earlier reference in the 1920s, stating that the term was used in the RAF to refer to a lowly menial person, such as a low-ranking officer or enlisted man saddled with oppressive assignments.

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