usage: a radioactive metallic element that is similar to tellurium and bismuth; occurs in uranium ores but can be produced by bombarding bismuth with neutrons in a nuclear reactor
2. polonium, Po, atomic number 84, metallic element, metal
usage: a European river; flows into the Adriatic Sea
3. Po, Po River
usage: an independent agency of the federal government responsible for mail delivery (and sometimes telecommunications) between individuals and businesses in the United States