15-Letter Words Matching F__________S___

There are 20 15-letter words that match F__________S___. 10 are common words, such as FACETIOUSNESSES and FAITHLESSNESSES. A rarer one is FUNCTIONALISTIC. 19 words contain a doubled letter.

Full list 20

facetiousnessesfaithlessnessesfaultlessnessesferociousnessesfoolhardinessesforgetfulnessesfractiousnessesfrightfulnessesfrivolousnessesfruitlessnessesfavorablenessesfideicommissaryfugaciousnessesfanaticalnessesfatheadednessesfeloniousnessesfencelessnessesforgivingnessesfortunatenessesfunctionalistic

About this list

Words
20 (10 common words)
Common example
facetiousnesses
Rare example
functionalistic
Doubled letters
19
Ending in S
18

Questions

How many 15-letter words matching f__________s___ are there?

20. 10 of them are common words.

What is a common example?

FACETIOUSNESSES is among the common words in this set.