15-Letter Words Matching __A__H_________

There are 12 15-letter words that match __A__H_________. 3 are common words, such as HEALTHFULNESSES and SLAUGHTERHOUSES. A rarer one is TRANSHISTORICAL. In this set, T is the most frequent open letter (11 words). 3 words contain a doubled letter.

Full list 12

healthfulnessesslaughterhouseswhatchamacallitunauthenticatedacanthocephalanfranchisabilityreauthorizationblasphemousnessplatyhelminthicstadtholderatesstadtholdershiptranshistorical

About this list

Words
12 (3 common words)
Common example
healthfulnesses
Rare example
transhistorical
Doubled letters
3
Ending in S
4
Most frequent letter
T (11)

Questions

How many 15-letter words matching __a__h_________ are there?

12. 3 of them are common words.

What is a common example?

HEALTHFULNESSES is among the common words in this set.