15-Letter Words Matching ________TR_____

There are 29 15-letter words that match ________TR_____. 6 are common words, such as PREREGISTRATION and THUNDERSTRICKEN. A rarer one is ULTRAFILTRATION. 3 words contain a doubled letter.

Full list 29

Common words

preregistrationthunderstrickentoastmistressesundemonstrativeunreconstructedweatherstrippedethnocentricityheliocentricityhousemistressespsychometricianpyroelectricityultracentrifuge
preregistrationthunderstrickentoastmistressesundemonstrativeunreconstructedweatherstrippedethnocentricityheliocentricityhousemistressespsychometricianpyroelectricityultracentrifugevasoconstrictorcounterstrategydeconcentratingdeconcentrationdorsiventralitydorsoventralityecocatastrophesmisregistrationoptoelectronicsoverconstructedpolyelectrolytereconcentratingreconcentrationreorchestratingreorchestrationthunderstrikingultrafiltration

About this list

Words
29 (6 common words)
Common example
preregistration
Rare example
ultrafiltration
Doubled letters
3
Ending in S
4

Questions

How many 15-letter words matching ________tr_____ are there?

29. 6 of them are common words.

What is a common example?

PREREGISTRATION is among the common words in this set.