A stem, in linguistics, is the combination of the basic form of a word (called the root) plus any derivational morphemes, but excluding inflectional elements. (This means, alternatively, that the stem is the form of the word to which inflectional morphemes can be added, if applicable.)

If the definition of a stem includes the possibility of zero derivation, then any root is also a stem. That is, if X is a root, then a stem X can be conceived as the root X plus a zero derivational affix.

Examples

The English root argu(e) gives the following stems (among others):

• argue (verb, zero derivation)
• argument (noun, with the addition of the derivational affix -ment)
• arguably (adverb, with the addition of the derivational affixes -able and -ly, fused into one)
• unarguably (adverb, built on arguably plus the negative affix un-)