There are at least four words that can follow ISOMORPH.
There is at least one word that can follow ISOMORPHS. We're seriously getting into Greek here...
There is at least one word that can follow APHORISMOS.
Add a K to get the next (Greek) word.
There are at least 5 words that can follow SHORTENS.
Southerns
I wouldn't have thought you could pluralize "Southern," but m-w recognizes it, and it's more interesting than "shortness"!
BUHRSTONES
There's at least one word that can follow.
