 The Slavonic word "robota" means serf-like servitude, forced labor, or drudgery; it was the 1920 Czech play "R. U. R." ("Rossumovi Univerzální Roboti") that introduced the cognate for "robot" into science fiction.In the play, the increasingly-capable synthetic servants, who "lack nothing but a soul", angrily and short-sightedly slaughter most of humanity during the course of their revolt, resulting in the loss of the secret of how to manufacture more robots.The robot race is saved, however, when two robots spontaneously acquire the traits of love and compassion and become able to reproduce.