Affix is a collective term for the type of morpheme that can be used only when added to another morpheme (the root or stem), so affix is natural bound. Affixes in a language are limited in number, and are generally classified into three subtypes, namely, prefix, suffix and infix, depending on their position around the root or stem of a word. For example, the word “impossible” has a prefix im- and a root “possible”; the word “kindness” has a suffix -ness and a root “kind”.