13-Letter Words Matching _I_________U_

There are 12 13-letter words that match _I_________U_. 4 are common words, such as DISCONTINUOUS and DISHARMONIOUS. A rarer one is MICROPHYLLOUS. In this set, S is the most frequent open letter (11 words). 4 words contain a doubled letter.

Full list 12

discontinuousdisharmoniousdisrespectfulmiscellaneousbignoniaceousdichlamydeouslissotrichousnickeliferoustintinnabulumbibliolatrousdiathermanousmicrophyllous

About this list

Words
12 (4 common words)
Common example
discontinuous
Rare example
microphyllous
Doubled letters
4
Ending in S
10
Most frequent letter
S (11)

Questions

How many 13-letter words matching _i_________u_ are there?

12. 4 of them are common words.

What is a common example?

DISCONTINUOUS is among the common words in this set.