15-Letter Words Matching __I_O__________

There are 17 15-letter words that match __I_O__________. 3 are common words, such as FRIVOLOUSNESSES and PHILOSOPHICALLY. A rarer one is UNIFORMITARIANS. In this set, O is the most frequent open letter (14 words). 5 words contain a doubled letter.

Full list 17

frivolousnessesphilosophicallytrigonometricalazidothymidinesoligonucleotideoligosaccharideaminopeptidasesanisotropicallyariboflavinosesariboflavinosisepizootiologiesoligodendrocyteoligodendrogliaoligomerizationoxidoreductasestrisoctahedronsuniformitarians

About this list

Words
17 (3 common words)
Common example
frivolousnesses
Rare example
uniformitarians
Doubled letters
5
Ending in S
9
Most frequent letter
O (14)

Questions

How many 15-letter words matching __i_o__________ are there?

17. 3 of them are common words.

What is a common example?

FRIVOLOUSNESSES is among the common words in this set.