10-Letter Words Matching _____O___C

There are 12 10-letter words that match _____O___C. 3 are common words, such as DIAGNOSTIC and PROGNOSTIC. A rarer one is SUPRAOPTIC. In this set, I is the most frequent open letter (12 words). 2 words contain a doubled letter.

Full list 12

diagnosticprognostictheosophicapotropaiccryptozoicdystrophicendodonticantipoeticblastodiscepiglotticisoglossicsupraoptic

About this list

Words
12 (3 common words)
Common example
diagnostic
Rare example
supraoptic
Doubled letters
2
Ending in S
0
Most frequent letter
I (12)

Questions

How many 10-letter words matching _____o___c are there?

12. 3 of them are common words.

What is a common example?

DIAGNOSTIC is among the common words in this set.