Derived stem

In Semitic languages, the entire vocabulary is based on a set of three or four consonants called a root. In those languages, derived stems are the ways of changing those roots to verbs.

For example, both in Arabic and in Hebrew, many words that have a meaning related to writing contain the root K-T-B (in Hebrew, when the letter B does not come at the beginning of a word, it may sound like a V). Thus, "he wrote" in Arabic is "hia kataba", "he dictated" is "hia kattaba", and "he corresponded" is "hia takātaba". Similarly, in Hebrew, "he wrote" is "hoo katav", "he dictated" is "hoo hichtiv", and "he corresponded" is "hoo hitkatev".

In each Semitic language, the number of common derived stems is different. In Hebrew there are seven common ones, in Arabic ten, in Asurian six and so on.