Newbie - Wikipedia, the free encyclopedia: "The word itself is probably a corruption of new boy; a new arrival in a school and who is, therefore, vulnerable to bullying of various kinds, such as hazing or fagging. It could also derive from 'new beginner'.

'Newbie' was used prior to this as slang in the U.S. Military to denote men who had finished technical school (so no longer a recruit and rookie) and were just arriving to their first permanent assignment."