gremlin: [20] Gremlin originated as Royal Air Force slang, as the name of a mischievous imp that caused malfunctions and crashes. It is first recorded in 1941, but it is said to go back to the early 1920s. It is generally assumed that its latter part comes from goblin, but speculation has been rife and diverse as to the source of its first syllable: from the scholarly (Old English gremman ‘make angry’) to the inventively popular (a blend of goblin with Fremlin, the name of a well-known firm of brewers).
