15-Letter Words Matching ____O______O___

There are 26 15-letter words that match ____O______O___. 4 are common words, such as IMPROVISATIONAL and MICROELECTRONIC. A rarer one is THYROCALCITONIN. In this set, I is the most frequent open letter (24 words). 4 words contain a doubled letter.

Full list 26

Common words

improvisationalmicroelectronicnitrocellulosesradiotelephonesadenocarcinomashydrocortisonesnoncommissionednonconventionalradiotelephonicariboflavinosesariboflavinosischemoautotrophy
improvisationalmicroelectronicnitrocellulosesradiotelephonesadenocarcinomashydrocortisonesnoncommissionednonconventionalradiotelephonicariboflavinosesariboflavinosischemoautotrophyglucocorticoidshistopathologicintrospectionallignocelluloseslignocellulosicmicroelectrodesmicrometeoroidsneuropathologicpentobarbitonesphenobarbitonesphotoautotrophsphotoelectronicphytoplanktonicthyrocalcitonin

About this list

Words
26 (4 common words)
Common example
improvisational
Rare example
thyrocalcitonin
Doubled letters
4
Ending in S
13
Most frequent letter
I (24)

Questions

How many 15-letter words matching ____o______o___ are there?

26. 4 of them are common words.

What is a common example?

IMPROVISATIONAL is among the common words in this set.