15-Letter Words Matching C_O____________

There are 20 15-letter words that match C_O____________. 1 are common words, such as COOPERATIVENESS and CHOLECALCIFEROL. A rarer one is CROTCHETINESSES. In this set, I is the most frequent open letter (17 words). 9 words contain a doubled letter.

Full list 20

cooperativenesscholecalciferolcholecystectomycholecystitideschoriocarcinomacrossopterygiancholangiographycholecystitisescholecystokinincholestyraminescholinergicallycholinesteraseschondrocraniumschordamesodermschorioallantoicchorioallantoiscloudlessnessescooperationistscrosslinguisticcrotchetinesses

About this list

Words
20 (1 common words)
Common example
cooperativeness
Rare example
crotchetinesses
Doubled letters
9
Ending in S
11
Most frequent letter
I (17)

Questions

How many 15-letter words matching c_o____________ are there?

20. 1 of them are common words.

What is a common example?

COOPERATIVENESS is among the common words in this set.