13-Letter Words Matching ____D_T______

There are 15 13-letter words that match ____D_T______. 3 are common words, such as EXPEDITIONARY and EXPEDITIOUSLY. A rarer one is HEREDITARIANS. In this set, I is the most frequent open letter (14 words). 3 words contain a doubled letter.

Full list 15

expeditionaryexpeditiouslygrandstandinggonadotropinshereditamentsoverdetermineanecdotalismsanecdotalistsanecdoticallyasyndeticallyfieldstrippedgonadotrophicgonadotrophingrandstandershereditarians

About this list

Words
15 (3 common words)
Common example
expeditionary
Rare example
hereditarians
Doubled letters
3
Ending in S
6
Most frequent letter
I (14)

Questions

How many 13-letter words matching ____d_t______ are there?

15. 3 of them are common words.

What is a common example?

EXPEDITIONARY is among the common words in this set.