9-Letter Words Matching _I_____F_

There are 12 9-letter words that match _I_____F_. 6 are common words, such as DISPROOFS and DIVERSIFY. A rarer one is RIFFRAFFS. In this set, S is the most frequent open letter (10 words). 6 words contain a doubled letter.

Full list 12

disproofsdiversifymischiefsnightlifepikestaffwindsurfsfisticuffkingcraftmineshafttipstaffsairproofsriffraffs

About this list

Words
12 (6 common words)
Common example
disproofs
Rare example
riffraffs
Doubled letters
6
Ending in S
6
Most frequent letter
S (10)

Questions

How many 9-letter words matching _i_____f_ are there?

12. 6 of them are common words.

What is a common example?

DISPROOFS is among the common words in this set.