12-Letter Words Matching ________AC__

There are 21 12-letter words that match ________AC__. 10 are common words, such as BIOFEEDBACKS and COMMONPLACES. A rarer one is METATHORACIC. In this set, S is the most frequent open letter (16 words). 4 words contain a doubled letter.

Full list 21

biofeedbackscommonplacescrackerjacksdiamondbacksmarketplacesmonomaniacalquarterbackssteeplejackssticklebackssubcontractsleatherbacksosteomalaciaparadisiacalpyromaniacalfluorouracilindomethacinletterspacesmesothoracesmesothoracicmetathoracesmetathoracic

About this list

Words
21 (10 common words)
Common example
biofeedbacks
Rare example
metathoracic
Doubled letters
4
Ending in S
13
Most frequent letter
S (16)

Questions

How many 12-letter words matching ________ac__ are there?

21. 10 of them are common words.

What is a common example?

BIOFEEDBACKS is among the common words in this set.