Argue
The longest words with these letters are only 4 letters long: data and tidy. The 3-letter words are add, aid, dad, day, did, and tad.
There are not many, but they include guide and guile and their related words.
manufactured, overabundant
boughs, coughs, roughs
46
2 or more
Fred Perry
Abandonment, abbreviated, abnormality, acclamation, adversaries and agriculture are words. They contain eleven letters.
The word "Inheritance" is 11 letters long.
There is no direct thirteen-letter anagram of the letters naigornutnema. The longest words you can make out of those letters are the eleven-letter long words nonargument and ornamenting.
The lack of consonants limits words to about 4 or 5 letters long. The longest words are fate, fete, feat, fiat, feta, and feet.
The longest English words you can make using only those letters are five-letter words: badge, cadge, caged, decaf, faced, fadge