A word in which no two letters are the same is often called an isogram. In an article in the August 1998 Word Ways, Eric Chaikin coined the term bisogram to identify word pairs in which no letters occur more than once. High-quality bisograms are essentially defined as those which contain only uncapitalized unhyphenated unabbreviated words which are listed in boldface type in Webster's Third; appropriate noun
"Wuthering Flapdocks! Yet More Bisograms,"
Word Ways: Vol. 32
, Article 4.
Available at: http://digitalcommons.butler.edu/wordways/vol32/iss2/4