stem can be a lone root, such as the verb run; a compound of roots, such as the compound nouns meatball and bottleneck; or a derivation with affixes, such as the verbs blacken and standardize.

The stem of the verb to wait is wait: The stem is the word part that is common to all of its inflected variants.
#wait (infinitive, imperative, present subjunctive, and present indicative except in the 3rd-person