9-Letter Words Matching ____N___M

There are 16 9-letter words that match ____N___M. 5 are common words, such as CONUNDRUM and GREENROOM. A rarer one is TARANTISM. In this set, I is the most frequent open letter (11 words). 3 words contain a doubled letter.

Full list 16

conundrumgreenroommisinformreconfirmstrontiumathenaeumcairngormcheongsamchernozemdecenniumdoronicumgigantismscientismtrienniummisoneismtarantism

About this list

Words
16 (5 common words)
Common example
conundrum
Rare example
tarantism
Doubled letters
3
Ending in S
0
Most frequent letter
I (11)

Questions

How many 9-letter words matching ____n___m are there?

16. 5 of them are common words.

What is a common example?

CONUNDRUM is among the common words in this set.