structural:expansion, information:classification
Other features

Roots are composed of only one morpheme, but stems can be composed of more than one morpheme. Any additional affixes are considered morphemes. For example, in the word quirkiness, the root is quirk, but the stem is quirky, which has two morphemes.

Moreover, some pairs of affixes have identical phonological form but different meanings. For example, the suffix -er can be either derivational (e.g. sell ⇒ seller) or inflectional (e.g. small ⇒ smaller). Such morphemes are called homophonous.

Some words might seem to be composed of multiple morphemes but are not. Therefore, not only form but also meaning must be considered when identifying morphemes. For example, the word Madagascar is long and might seem to have morphemes like mad, gas, and car, but it does not. Conversely, some short words have multiple morphemes (e.g. dogs = dog + s).