15-Letter Words Matching ____O_____N____

There are 23 15-letter words that match ____O_____N____. 3 are common words, such as PREPOSITIONALLY and SERVOMECHANISMS. A rarer one is STEROIDOGENESIS. In this set, I is the most frequent open letter (21 words). 4 words contain a doubled letter.

Full list 23

prepositionallyservomechanismsunsportsmanlikeadenocarcinomasgluconeogenesisglyconeogenesismicrosporangiumnonconfidentialphotomechanicalservomechanicalariboflavinosesariboflavinosiscompositionallyferromanganesesgluconeogeneseshydromechanicallignosulfonatesoutdoorsmanshipoveropinionatedoverornamentingpreponderanciessteroidogenesessteroidogenesis

About this list

Words
23 (3 common words)
Common example
prepositionally
Rare example
steroidogenesis
Doubled letters
4
Ending in S
12
Most frequent letter
I (21)

Questions

How many 15-letter words matching ____o_____n____ are there?

23. 3 of them are common words.

What is a common example?

PREPOSITIONALLY is among the common words in this set.