in Internet sense, c.2000, short for robot
. Its modern use has curious affinities with earlier uses, e.g. "parasitical worm or maggot (1520s), of unknown origin; and Australian-N.Z. slang "worthless, troublesome person" (World War I-era). The method of minting new slang by clipping the heads off respectable words does not seem to be old or widespread in English. Examples (za
) are Amer.Eng. student or teen slang and seem to date back no further than late 1960s.