СОБ

СОБ is a Russian root meaning "self; one's own." It comes from an Indo-European root with roughly the same meaning. "Suicide" and "self" are cognates. (Remember Grimm's law for that last one.)

Today's word:
особенный - special, peculiar

(I'm not exactly clear on what "special" has to do with "self," but my dictionary of Russian roots says they're related.)