15-Letter Words Matching ___OS__________

There are 18 15-letter words that match ___OS__________. 3 are common words, such as ATMOSPHERICALLY and HOMOSEXUALITIES. A rarer one is UNFOSSILIFEROUS. In this set, I is the most frequent open letter (17 words). 8 words contain a doubled letter.

Full list 18

atmosphericallyhomosexualitiesimpossibilitiesautosuggestionsgyrostabilizersmonosaccharidesaerosolizationshexosaminidaseshyposensitizinghypostatizationinhospitalitiesionosphericallymonospecificitymonosyllabicityrehospitalizingreposefulnessestenosynovitisesunfossiliferous

About this list

Words
18 (3 common words)
Common example
atmospherically
Rare example
unfossiliferous
Doubled letters
8
Ending in S
11
Most frequent letter
I (17)

Questions

How many 15-letter words matching ___os__________ are there?

18. 3 of them are common words.

What is a common example?

ATMOSPHERICALLY is among the common words in this set.