Synonyms for po Found 8 synonyms across 4 meanings for “po”. a radioactive metallic element that is similar to tellurium and bismuth (noun) polonium a noncommissioned officer in the Navy or Coast Guard with a rank comparable to sergeant in the Army (noun) p.o. a European river (noun) an independent agency of the federal government responsible for mail delivery (and sometimes telecommunications) between individuals and businesses in the United States (noun) Explore Related Words Rhymes with poSynonyms for poloniumSynonyms for p.o. Synonym Finder | Rhyme Finder | Poetry Editor