The words “I” and “a” are universally-annagrammable: every possible arrangement of letters in the words (or permutation, or anagram) is an English word. Of course, since there’s only one way to arrange the letters in a one-letter word, that’s not very remarkable.
For two-letter words, “on” is universally anagrammable: "on and “no” are words, and those are the only two permutations of the word. If we go by Scrabble words, there are a few others (I’ll only list one word in the anagram set for these, as finding the others is trivial): he, we, oh, ma, me, and so on.
Then we get to three-letter words. Each three-letter set has six permutations. Are there any universally-anagrammable three-letter words?
The closest I could find is “spa”: asp, pas, sap, spa. “PSA” is a common abbreviation, and if we squint and consider “ap” an abbreviation for “apostle,” we could get “aps.” But those last two are bogus in my opinion.
I’m strongly doubtful that there are any four-letter universally-anagrammable words (24 permutations), and would bet a buncha Internet cookies that there are no five-letter words with 119 anagrams. Which brings me to my next question:
For word lengths greater than three letters, what words at each letter length have the most anagrams?
That is, what four-letter word has the most anagrams? What five-letter word has the most anagrams? And so on.
I’m not sure what authority we should use for what constitutes a legit word; for now, maybe use the Scrabble dictionary?
I put this in thread games because although there are objective answers, I don’t know that that’s the most fun way to find it. (While typing that sentence I searched, and someone’s run a Python script to find the answers–but it might be more fun to see what y’all get).