Tin and Fur are two possibilities.
calico, muslin, damask
total
The word, "mineral," can be spelled using only the letters found in the word, "parliament."
extra, waste, scrap
wholesome
There is no word that can consist of 7 consonants and only have 3 letters. Consonants are letters.
Strength is the only English word you can spell with those letters.
snowday
The only word I can think of for "joker", 3-letters, is imp.
The only English word you can make with those letters is oe.
Yes, protozoan is the only word you can make with those letters.
sultana