Imur, I think that firma is in M-W only as part of the phrase terra firma. I'm not sure it qualifies as an acceptable word on it's own.
You are probably right, firefly. Just thought "firms" was too boring..
firms
There are at least two words that can follow FIRMEST.
There is at least one word that can follow FURMITIES.
There is, amazingly, at least one word that can follow CHIASMUS.
Add a U to CHIASMUS to get the next word. It's a place name and the word is hyphenated.
OK Bree what does it mean - sounds like a dish on a Thai menu