R-bomb noun 2verb 1forms 7 noun2 •Any of various shocking or offensive words starting with the letter R.When White House chief of staff Rahm Emanuel said a group of liberal activists were "fucking retarded," he was roundly condemned for dropping an R-bomb that way. — 2010 •A relativistic kinetic weapon. verb1 •(slang) To leave someone's text message on read without replying.Being r-bombed is roughhh — 2010 formsR bombed · R-bombed · r-bombed · R-bombing · R bombs · R-bombs · r-bombs