15-Letter Words Matching ____O_R________

There are 21 15-letter words that match ____O_R________. 3 are common words, such as APPROPRIATENESS and DISCOURAGEMENTS. A rarer one is RETROGRADATIONS. In this set, I is the most frequent open letter (21 words). 12 words contain a doubled letter.

Full list 21

appropriatenessdiscouragementsmicroprocessorsmalnourishmentsphototransistorretrogressivelyanisotropicallymicroprojectionmicroprojectorsmiscorrelationsnoncorrelationsopprobriousnessoutdoorsmanshipphonogramicallyphotogrammetricphotoproductionphototropicallyplutocraticallyradioprotectionradioprotectiveretrogradations

About this list

Words
21 (3 common words)
Common example
appropriateness
Rare example
retrogradations
Doubled letters
12
Ending in S
9
Most frequent letter
I (21)

Questions

How many 15-letter words matching ____o_r________ are there?

21. 3 of them are common words.

What is a common example?

APPROPRIATENESS is among the common words in this set.