This document defines and categorizes different types of morphemes including roots, affixes, stems, and bases. It provides the following information:
1) A morpheme is the smallest meaningful linguistic unit that cannot be further divided. There are two main types: root morphemes which have individual lexical meanings, and affixational morphemes which carry grammatical meaning.
2) A root is the base form of a word that retains its identity when affixes are removed. A stem includes the root plus any derivational affixes to which inflectional affixes can be added.
3) Affixes are bound morphemes that can only be used in combination