A stem is the root or roots of a word, together with any derivational affixes, to which inflectional affixes are added.
A stem consists minimally of a root, but may be analyzable into a root plus derivational morphemes. A stem may require an inflectional operation (often involving a prefix or suffix) in order to ground it into discourse and make it a fully understandable word. If a stem does not occur by itself in a meaningful way in a language, it is referred to as a bound morpheme.
- The verbs tie and untie are both stems.
- The inflectional third person singular suffix -s may be added to the stems to form ties and unties.