15-Letter Words Matching ___T_____R_____

There are 18 15-letter words that match ___T_____R_____. 4 are common words, such as HISTORIOGRAPHER and PARTICULARITIES. A rarer one is POSTMASTERSHIPS. In this set, I is the most frequent open letter (17 words). 3 words contain a doubled letter.

Full list 18

historiographerparticularitiesparticularizingweatherstrippedcontrollershipshistoriographicinstructorshipsmultilateralismmultilateralistmistranscribingmouthwateringlymultipolaritiesparticularisingparticularisticphytogeographerphytogeographicposthemorrhagicpostmasterships

About this list

Words
18 (4 common words)
Common example
historiographer
Rare example
postmasterships
Doubled letters
3
Ending in S
5
Most frequent letter
I (17)

Questions

How many 15-letter words matching ___t_____r_____ are there?

18. 4 of them are common words.

What is a common example?

HISTORIOGRAPHER is among the common words in this set.