A morph is a minimal unit of meaning or grammatical function in a language. It is the smallest unit of a word that carries meaning.
For example, in the word "unhappiness," there are three morphs: "un-" which indicates negation, "-happy" which indicates the root word "happy," and "-ness" which indicates the noun form of the word. Each of these morphs carries a specific meaning or function within the word.
Another example is the word "cats." In this word, there are two morphs: "cat" which is the root word, and "-s" which indicates pluralization. Each of these morphs contributes to the overall meaning and function of the word.