15-Letter Words Matching __________T_R__

There are 20 15-letter words that match __________T_R__. 3 are common words, such as COUNTERCULTURES and INFRASTRUCTURES. A rarer one is ULTRASTRUCTURES. In this set, U is the most frequent open letter (18 words). 0 words contain a doubled letter.

Full list 20

counterculturesinfrastructuressuperstructuresanticholesterolinfrastructuralnonagriculturalpreagriculturalsuperstructuralcounterculturaldistemperaturesmacrostructuralmacrostructuresmaladministeredmicrostructuralmicrostructurespremanufacturedpremanufacturesultimogenituresultrastructuralultrastructures

About this list

Words
20 (3 common words)
Common example
countercultures
Rare example
ultrastructures
Doubled letters
0
Ending in S
9
Most frequent letter
U (18)

Questions

How many 15-letter words matching __________t_r__ are there?

20. 3 of them are common words.

What is a common example?

COUNTERCULTURES is among the common words in this set.