15-Letter Words Matching _____S___T_____

There are 18 15-letter words that match _____S___T_____. 6 are common words, such as DEMONSTRATIVELY and DISRESPECTFULLY. A rarer one is UNSUBSTANTIALLY. In this set, I is the most frequent open letter (17 words). 6 words contain a doubled letter.

Full list 18

demonstrativelydisrespectfullyinsubstantiallyintrospectivelyretrospectivelyunsubstantiatedecclesiasticisminterstratifiedinterstratifiesnecessaritariancommiseratinglydemonstrationalintrospectionalorchestrationalremonstrativelysacrosanctitiessuperspectaclesunsubstantially

About this list

Words
18 (6 common words)
Common example
demonstratively
Rare example
unsubstantially
Doubled letters
6
Ending in S
3
Most frequent letter
I (17)

Questions

How many 15-letter words matching _____s___t_____ are there?

18. 6 of them are common words.

What is a common example?

DEMONSTRATIVELY is among the common words in this set.