11-Letter Words Matching O________R_

There are 20 11-letter words that match O________R_. 8 are common words, such as OBSERVATORY and OFFICIATORS. A rarer one is OXYGENATORS. 5 words contain a doubled letter.

Full list 20

observatoryofficiatorsoriginatorsoscillatorsoscillatoryoutfieldersovermastersoverwintersobfuscatoryobjurgatoryommatophoreostracodermoverconcernovermeasureovipositorsozonosphereobstructorsoutdeliversoutglittersoxygenators

About this list

Words
20 (8 common words)
Common example
observatory
Rare example
oxygenators
Doubled letters
5
Ending in S
11

Questions

How many 11-letter words matching o________r_ are there?

20. 8 of them are common words.

What is a common example?

OBSERVATORY is among the common words in this set.