15-Letter Words Matching ____S________S_

There are 12 15-letter words that match ____S________S_. 5 are common words, such as FORESIGHTEDNESS and ILLUSTRIOUSNESS. A rarer one is UNDESIRABLENESS. 10 words contain a doubled letter.

Full list 12

foresightednessillustriousnessindustriousnessnearsightednesspraiseworthiestunassertivenesslongsightednessnecessitousnessnonpsychiatristpleasurablenesstransparentnessundesirableness

About this list

Words
12 (5 common words)
Common example
foresightedness
Rare example
undesirableness
Doubled letters
10
Ending in S
10

Questions

How many 15-letter words matching ____s________s_ are there?

12. 5 of them are common words.

What is a common example?

FORESIGHTEDNESS is among the common words in this set.