13-Letter Words Matching ____C___O____

There are 20 13-letter words that match ____C___O____. 6 are common words, such as EFFICACIOUSLY and ENDOCRINOLOGY. A rarer one is POLYCHOTOMOUS. In this set, N is the most frequent open letter (16 words). 6 words contain a doubled letter.

Full list 20

efficaciouslyendocrinologyimpecuniouslyinsectivorousreincorporatetreacherouslyallochthonousanticlinoriumanticorrosiveautochthonousillocutionaryimpecuniositypolycarbonateanticorporateanticorrosionchancelloriesdodecaphoniesdodecaphonistpolychotomiespolychotomous

About this list

Words
20 (6 common words)
Common example
efficaciously
Rare example
polychotomous
Doubled letters
6
Ending in S
7
Most frequent letter
N (16)

Questions

How many 13-letter words matching ____c___o____ are there?

20. 6 of them are common words.

What is a common example?

EFFICACIOUSLY is among the common words in this set.