13-Letter Words Matching O_________N__

There are 20 13-letter words that match O_________N__. 6 are common words, such as OBSERVATIONAL and OUTPLACEMENTS. A rarer one is OVIPOSITIONAL. In this set, E is the most frequent open letter (17 words). 3 words contain a doubled letter.

Full list 20

observationaloutplacementsoverabundanceovercrowdingsoveremotionaloxyacetylenesorientationalovertightenedopisthobranchorienteeringsoscillationalovercautionedoverconcernedoverdiscountsoverdocumentsoverdominanceoverexplainedoverornamentsoversweetenedovipositional

About this list

Words
20 (6 common words)
Common example
observational
Rare example
ovipositional
Doubled letters
3
Ending in S
7
Most frequent letter
E (17)

Questions

How many 13-letter words matching o_________n__ are there?

20. 6 of them are common words.

What is a common example?

OBSERVATIONAL is among the common words in this set.