12-Letter Words Matching O_________A_

There are 12 12-letter words that match O_________A_. 6 are common words, such as OBSTETRICIAN and OCCUPATIONAL. A rarer one is OSTEOLOGICAL. In this set, I is the most frequent open letter (11 words). 2 words contain a doubled letter.

Full list 12

obstetricianoccupationaloctogenarianoligarchicalorthodontiasovercriticaloppositionalorographicaloverfamiliaronomasticianonychophoranosteological

About this list

Words
12 (6 common words)
Common example
obstetrician
Rare example
osteological
Doubled letters
2
Ending in S
1
Most frequent letter
I (11)

Questions

How many 12-letter words matching o_________a_ are there?

12. 6 of them are common words.

What is a common example?

OBSTETRICIAN is among the common words in this set.