Horrendous is 1 word
8^5=32,768 if letters can repeat 2,880 if letters can not be repeated.
Frost.
boughs, coughs, roughs
There are no 5 letter words containing uu. The 6 letter word vacuum is the shortest word that contains the letters uu.
Horrendous is 1 word
Earth
The longest words are 5 letters: curve, creme, and revue.
8^5=32,768 if letters can repeat 2,880 if letters can not be repeated.
Kid stuff
Frost.
boughs, coughs, roughs
There is no 5-letter English word using the letters THRIK. The letters can spell the shorter words irk, hit, kit, and kith.
I cannot find any words that use all 5 letters. The letters can be used to spell try and my.
No seven letter word, the longest words are 5 letters: carob, corgi, cigar, cobra, cargo
There are no 5 letter words containing uu. The 6 letter word vacuum is the shortest word that contains the letters uu.
No 7 letter words there. 5 letters is the best you can do: arena or anear