12-Letter Words Matching ___I_____U__

There are 18 12-letter words that match ___I_____U__. 5 are common words, such as ARBITRAGEURS and CALIFORNIUMS. A rarer one is POSITRONIUMS. In this set, R is the most frequent open letter (17 words). 4 words contain a doubled letter.

Full list 18

arbitrageurscaliforniumsequilibriumspericardiumsredistributeacciaccaturaantirrhinumsheliogravurejurisconsultunnilhexiumsvenipunctureantidandruffantipleasuremagisteriumsmagistratureoutintriguedoutintriguespositroniums

About this list

Words
18 (5 common words)
Common example
arbitrageurs
Rare example
positroniums
Doubled letters
4
Ending in S
9
Most frequent letter
R (17)

Questions

How many 12-letter words matching ___i_____u__ are there?

18. 5 of them are common words.

What is a common example?

ARBITRAGEURS is among the common words in this set.