15-Letter Words Matching I________I_____

There are 13 15-letter words that match I________I_____. 6 are common words, such as IMMUNODEFICIENT and INAPPROPRIATELY. A rarer one is IONOSPHERICALLY. 9 words contain a doubled letter.

Full list 13

immunodeficientinappropriatelyinfinitesimallyinsurrectionistinterventionisminterventionistimmunologicallyinsurrectionaryideographicallyindisciplinableinefficaciouslyinterprovincialionospherically

About this list

Words
13 (6 common words)
Common example
immunodeficient
Rare example
ionospherically
Doubled letters
9
Ending in S
0

Questions

How many 15-letter words matching i________i_____ are there?

13. 6 of them are common words.

What is a common example?

IMMUNODEFICIENT is among the common words in this set.