What does stem mean in English grammar?

Answer 1

The stem of a word is the portion that doesn't change regardless of tense or agreement. Some examples*:

-stem-

stem{s}

stem(s)

stem(med)

stem(ming)

-bill-

bill{s}

bill(s)

bill(ed)

bill(ing)

[under]bill(ed)

[re]bill

Stems are also a feature of colloquial noun-verb adaptations, such as "text," "blog," or "impact." Because these "verbs" began as whole-word nouns, rather than developing as infinitive verbs, the stem is always the whole word.

*

{agreement}

(suffix/tense)

[prefix/qualifier]