14-Letter Words Matching A_______O_____

There are 21 14-letter words that match A_______O_____. 5 are common words, such as ACETAMINOPHENS and AMBASSADORSHIP. A rarer one is AUTORADIOGRAMS. In this set, I is the most frequent open letter (20 words). 7 words contain a doubled letter.

Full list 21

acetaminophensambassadorshiparchaeologicalarchaeologistsarchbishopricsacetylcholinesanamorphoscopearchdeaconriesautoradiographadaptationallyaerobiologicalagglutinogenicaldosteronismsannexationistsanticensorshipanticorrosivesantihistoricalantimicrobialsantiterrorismsantiterroristsautoradiograms

About this list

Words
21 (5 common words)
Common example
acetaminophens
Rare example
autoradiograms
Doubled letters
7
Ending in S
12
Most frequent letter
I (20)

Questions

How many 14-letter words matching a_______o_____ are there?

21. 5 of them are common words.

What is a common example?

ACETAMINOPHENS is among the common words in this set.