13-Letter Words Matching __A_________T

There are 12 13-letter words that match __A_________T. 5 are common words, such as FEATHERWEIGHT and GRANDILOQUENT. A rarer one is PLANETOLOGIST. In this set, I is the most frequent open letter (10 words). 3 words contain a doubled letter.

Full list 12

featherweightgrandiloquentreappointmentrearrangementtransshipmentclavichordistfranchisementleatherjacketthanatologistthaumaturgistdiabetologistplanetologist

About this list

Words
12 (5 common words)
Common example
featherweight
Rare example
planetologist
Doubled letters
3
Ending in S
0
Most frequent letter
I (10)

Questions

How many 13-letter words matching __a_________t are there?

12. 5 of them are common words.

What is a common example?

FEATHERWEIGHT is among the common words in this set.