7-Letter Words Matching ____R_O

There are 12 7-letter words that match ____R_O. 5 are common words, such as CHEERIO and EMBARGO. A rarer one is ZAMARRO. In this set, E is the most frequent open letter (9 words). 3 words contain a doubled letter.

Full list 12

cheerioembargoinfernoscherzoundergoespartopotorooreversotheorbotamaraounderdozamarro

About this list

Words
12 (5 common words)
Common example
cheerio
Rare example
zamarro
Doubled letters
3
Ending in S
0
Most frequent letter
E (9)

Questions

How many 7-letter words matching ____r_o are there?

12. 5 of them are common words.

What is a common example?

CHEERIO is among the common words in this set.