11-Letter Words Matching O________A_

There are 15 11-letter words that match O________A_. 4 are common words, such as OBSESSIONAL and OBSTETRICAL. A rarer one is OVERPROGRAM. In this set, L is the most frequent open letter (12 words). 3 words contain a doubled letter.

Full list 15

obsessionalobstetricalontologicaloperationaloncologicalophthalmiasorthonormalorthopteranoscillogramoverliberaloecumenicaloutdoorsmanoverarousaloverliteraloverprogram

About this list

Words
15 (4 common words)
Common example
obsessional
Rare example
overprogram
Doubled letters
3
Ending in S
1
Most frequent letter
L (12)

Questions

How many 11-letter words matching o________a_ are there?

15. 4 of them are common words.

What is a common example?

OBSESSIONAL is among the common words in this set.