An isogram, in which all letters occur an equal number of times, is the same as a heterogram when each letter occurs once.

Conveniently, the word itself is an isogram.

An isogram (also known as a "nonpattern word") is a logological term for a word or phrase without a repeating letter.

It is famous because it is a perfect pangram (and in the same time an isogram), containing each character of the Japanese syllabary exactly once.