13-Letter Words Matching O________O___

There are 14 13-letter words that match O________O___. 4 are common words, such as OBSERVATIONAL and OSCILLOSCOPES. A rarer one is OXYHEMOGLOBIN. 4 words contain a doubled letter.

Full list 14

observationaloscilloscopesoverdevelopedoveremotionalorientationalorthohydrogenoscilloscopicorthopteroidsoscillationalosteosarcomasovercautionedoverwithholdsovipositionaloxyhemoglobin

About this list

Words
14 (4 common words)
Common example
observational
Rare example
oxyhemoglobin
Doubled letters
4
Ending in S
4

Questions

How many 13-letter words matching o________o___ are there?

14. 4 of them are common words.

What is a common example?

OBSERVATIONAL is among the common words in this set.