13-Letter Words Matching _OP__________

There are 21 13-letter words that match _OP__________. 7 are common words, such as COPIOUSNESSES and FOPPISHNESSES. A rarer one is TOPLESSNESSES. In this set, I is the most frequent open letter (18 words). 9 words contain a doubled letter.

Full list 21

copiousnessesfoppishnesseshopefulnessessophisticatedsophisticatessoporificallytopographicaltopologicallycopartnershipcopolymerizedcopolymerizescopyrightablesophisticallycoparcenariescoplanaritiescoprocessingscoproductionscoprophiliacscoproprietorsdoppelgangerstoplessnesses

About this list

Words
21 (7 common words)
Common example
copiousnesses
Rare example
toplessnesses
Doubled letters
9
Ending in S
13
Most frequent letter
I (18)

Questions

How many 13-letter words matching _op__________ are there?

21. 7 of them are common words.

What is a common example?

COPIOUSNESSES is among the common words in this set.