12-Letter Words Matching O_________U_

There are 13 12-letter words that match O_________U_. 4 are common words, such as OBSTREPEROUS and OSTENTATIOUS. A rarer one is ONCORNAVIRUS. In this set, O is the most frequent open letter (12 words). 0 words contain a doubled letter.

Full list 13

obstreperousostentatiousovercautiousovergenerousorchidaceousorthopterousorthotropousoverdesirousoverfancifuloverpowerfuloleoresinousoligophagousoncornavirus

About this list

Words
13 (4 common words)
Common example
obstreperous
Rare example
oncornavirus
Doubled letters
0
Ending in S
11
Most frequent letter
O (12)

Questions

How many 12-letter words matching o_________u_ are there?

13. 4 of them are common words.

What is a common example?

OBSTREPEROUS is among the common words in this set.