15-Letter Words Matching __A_I__________

There are 20 15-letter words that match __A_I__________. 5 are common words, such as EGALITARIANISMS and INANIMATENESSES. A rarer one is WEARISOMENESSES. 10 words contain a doubled letter.

Full list 20

egalitarianismsinanimatenessesmeaninglessnesstraditionalismstraditionalistscharismaticallygravimetricallygravitationallyimaginativenessdeacidificationimaginarinessespharisaicalnessplanimetricallyplatinocyanidesplatitudinarianplatitudinizingplatitudinouslytraditionalizedtraditionalizeswearisomenesses

About this list

Words
20 (5 common words)
Common example
egalitarianisms
Rare example
wearisomenesses
Doubled letters
10
Ending in S
11

Questions

How many 15-letter words matching __a_i__________ are there?

20. 5 of them are common words.

What is a common example?

EGALITARIANISMS is among the common words in this set.