15-Letter Words Matching ____T_____O____

There are 14 15-letter words that match ____T_____O____. 4 are common words, such as CONSTITUTIONALS and CONSTRUCTIONIST. A rarer one is SUBSTITUTIONARY. In this set, S is the most frequent open letter (13 words). 3 words contain a doubled letter.

Full list 14

constitutionalsconstructionistphantasmagoriassanctimoniouslyautotransformercountermelodiesprostatectomiescounterreformercryptozoologiescryptozoologistelectrodepositsroentgenologiesroentgenologistsubstitutionary

About this list

Words
14 (4 common words)
Common example
constitutionals
Rare example
substitutionary
Doubled letters
3
Ending in S
7
Most frequent letter
S (13)

Questions

How many 15-letter words matching ____t_____o____ are there?

14. 4 of them are common words.

What is a common example?

CONSTITUTIONALS is among the common words in this set.