15-Letter Words Matching _R________O____

There are 13 15-letter words that match _R________O____. 4 are common words, such as PRECONDITIONING and PRESERVATIONIST. A rarer one is PREFORMATIONIST. 4 words contain a doubled letter.

Full list 13

preconditioningpreservationisttroubleshooterstroubleshootingarchiepiscopacyarchiepiscopatepresentationismpreservationismprostatectomiescryptozoologiescryptozoologistprecipitinogenspreformationist

About this list

Words
13 (4 common words)
Common example
preconditioning
Rare example
preformationist
Doubled letters
4
Ending in S
4

Questions

How many 15-letter words matching _r________o____ are there?

13. 4 of them are common words.

What is a common example?

PRECONDITIONING is among the common words in this set.