Morpheme

One or more phonemes that combine to make a semantic unit that is not divisible into smaller sematic units.----

Again this is the minimal unit of meaning in a particular language, as determined by word pairs. For example, compare "athropy" and "dystrophy." Also, "euphoria" and dysphoria." Since "dys" distinguishes these pairs of words, "dys" is probably a morpheme.

It doesn't appear it can be further divided.