15-Letter Words Matching ____NI_________

There are 12 15-letter words that match ____NI_________. 4 are common words, such as ADMINISTRATIONS and HUMANITARIANISM. A rarer one is PERSNICKETINESS. 6 words contain a doubled letter.

Full list 12

administrationshumanitarianisminfinitesimallyingeniousnessessaponificationsammonificationscolonizationistfeloniousnessesnonuniformitiesnonuniquenessesnonuniversitiespersnicketiness

About this list

Words
12 (4 common words)
Common example
administrations
Rare example
persnicketiness
Doubled letters
6
Ending in S
9

Questions

How many 15-letter words matching ____ni_________ are there?

12. 4 of them are common words.

What is a common example?

ADMINISTRATIONS is among the common words in this set.