According to Wikepedia, here:
R.U.R. is a 1920 science fiction play by the Czech writer Karel Čapek. R.U.R. stands for Rossumovi Univerzální Roboti (Rossum’s Universal Robots). However, the English phrase Rossum’s Universal Robots had been used as the subtitle in the Czech original. It premiered on 25 January 1921 and introduced the word "robot" to the English language and to science fiction as a whole.I've posted here many times about R.U.R. and it's influence on Robotics Under the Stole, especially the RUS favicon. Above are photos of the Cover and Title Page of R.U.R. and below is the RUS favicon.