12-Letter Words Matching _____R___U__

There are 13 12-letter words that match _____R___U__. 5 are common words, such as ARBITRAGEURS and CARBORUNDUMS. A rarer one is SEMPERVIVUMS. In this set, S is the most frequent open letter (13 words). 4 words contain a doubled letter.

Full list 13

arbitrageurscarborundumsinterregnumslitterateurssubstructureantheridiumsantirrhinumsclostridiumsoverpressurepositroniumspostfractureprestructuresempervivums

About this list

Words
13 (5 common words)
Common example
arbitrageurs
Rare example
sempervivums
Doubled letters
4
Ending in S
9
Most frequent letter
S (13)

Questions

How many 12-letter words matching _____r___u__ are there?

13. 5 of them are common words.

What is a common example?

ARBITRAGEURS is among the common words in this set.