15-Letter Words Matching H_____I________

There are 12 15-letter words that match H_____I________. 3 are common words, such as HALLUCINOGENICS and HEARTSICKNESSES. A rarer one is HYPNOTIZABILITY. In this set, I is the most frequent open letter (10 words). 5 words contain a doubled letter.

Full list 12

hallucinogenicsheartsicknesseshistoriographerhallucinationalhistoriographichousemistresseshousewifelinesshydrobiologicalhydrobiologistshyperlipidemiashypervigilanceshypnotizability

About this list

Words
12 (3 common words)
Common example
hallucinogenics
Rare example
hypnotizability
Doubled letters
5
Ending in S
7
Most frequent letter
I (10)

Questions

How many 15-letter words matching h_____i________ are there?

12. 3 of them are common words.

What is a common example?

HALLUCINOGENICS is among the common words in this set.