5-Letter Words Matching A___O

There are 13 5-letter words that match A___O. 4 are common words, such as ACHOO and ALTHO. A rarer one is AZIDO. In this set, I is the most frequent open letter (7 words). 2 words contain a doubled letter.

Full list 13

achooalthoamigoaudioaminoabmhoaggroamnioadoboalamoamidoavisoazido

About this list

Words
13 (4 common words)
Common example
achoo
Rare example
azido
Doubled letters
2
Ending in S
0
Most frequent letter
I (7)

Questions

How many 5-letter words matching a___o are there?

13. 4 of them are common words.

What is a common example?

ACHOO is among the common words in this set.