9-Letter Words Matching ____Y___M

There are 12 9-letter words that match ____Y___M. 5 are common words, such as ECOSYSTEM and MARTYRDOM. A rarer one is PTERYGIUM. 1 words contain a doubled letter.

Full list 12

ecosystemmartyrdomneodymiumpachydermsubsystemcollyriumsyncytiumuropygiumepimysiumlathyrismnonsystempterygium

About this list

Words
12 (5 common words)
Common example
ecosystem
Rare example
pterygium
Doubled letters
1
Ending in S
0

Questions

How many 9-letter words matching ____y___m are there?

12. 5 of them are common words.

What is a common example?

ECOSYSTEM is among the common words in this set.