12-Letter Words Starting With OP

There are 20 12-letter words that start with OP. 8 are common words, such as OPALESCENCES and OPAQUENESSES. A rarer one is OPTIMISATION. 9 words contain a doubled letter.

Full list 20

opalescencesopaquenessesoperaticallyopportunismsopportunistsoppressivelyoptimizationoptometristsopenhandedlyophthalmitisopinionativeopposabilityoppositenessoppositionalopalescentlyoperationismoperationistoperatorlessoptimalitiesoptimisation

About this list

Words
20 (8 common words)
Common example
opalescences
Rare example
optimisation
Doubled letters
9
Ending in S
9

Questions

How many 12-letter words starting with op are there?

20. 8 of them are common words.

What is a common example?

OPALESCENCES is among the common words in this set.