15-Letter Words Matching ______A__O_____

There are 21 15-letter words that match ______A__O_____. 2 are common words, such as INTERNATIONALLY and SEGREGATIONISTS. A rarer one is RESERVATIONISTS. In this set, I is the most frequent open letter (21 words). 12 words contain a doubled letter.

Full list 21

internationallysegregationistscomputationallyassociationismscoeducationallyconjugationallygravitationallyinspirationallyobservationallyassociationistscooperationistshistopathologicinformationallyintegrationistsmicroradiographneuropathologicnonmetaphoricalorientationallyphytopathogenicrepudiationistsreservationists

About this list

Words
21 (2 common words)
Common example
internationally
Rare example
reservationists
Doubled letters
12
Ending in S
7
Most frequent letter
I (21)

Questions

How many 15-letter words matching ______a__o_____ are there?

21. 2 of them are common words.

What is a common example?

INTERNATIONALLY is among the common words in this set.