1. 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 Noun
2. A noncommissioned officer in the Navy or Coast Guard with a rank comparable to sergeant in the Army Noun
3. A European river; flows into the Adriatic Sea Noun
4. An independent agency of the federal government responsible for mail delivery (and sometimes telecommunications) between individuals and businesses in the United States Noun