12-Letter Words Matching O_________S_

There are 23 12-letter words that match O_________S_. 8 are common words, such as OBDURATENESS and OBSCURANTISM. A rarer one is OVEROPTIMIST. 10 words contain a doubled letter.

Full list 23

obduratenessobscurantismobscurantistordinarinessorthodontistorthopaedistoverexerciseoveroptimismobligingnessobsoletenessodontologistoppositenessoverinterestoceanologistoperationismoperationistoperatorlessorthopteristoutdatednessoutgoingnessoutsidernessovercompressoveroptimist

About this list

Words
23 (8 common words)
Common example
obdurateness
Rare example
overoptimist
Doubled letters
10
Ending in S
10

Questions

How many 12-letter words matching o_________s_ are there?

23. 8 of them are common words.

What is a common example?

OBDURATENESS is among the common words in this set.