It is a peculiarity of Semitic linguistics that a large majority of these consonantal roots are triliterals (although there are a number of quadriliterals, and in some languages also biliterals).
The following are some of the forms which can be derived from the triconsonantal root k-t-b כ־ת־ב ك-ت-ب (general overall meaning "to write") in Hebrew and Arabic: The Hebrew fricatives stemming from begadkefat lenition are transcribed here as "ḵ", "ṯ" and "ḇ", to retain their connection with the consonantal root כ־ת־ב k-t-b.
The Arabic terms, called وزن wazan (plural أوزان, awzān) for the pattern and جذر jiḏr (plural جذور, juḏūr) for the root have not gained the same currency in cross-linguistic Semitic scholarship as the Hebrew equivalents, and Western grammarians continue to use "stem"/"form"/"pattern" for the former and "root" for the latter—though "form" and "pattern" are accurate translations of the Arabic grammatical term wazan (originally meaning 'weight, measure'), and "root" is a literal translation of jiḏr.
the relation between: The Hebrew root ש־ק־ף – √sh-q-p "look out/through" or "reflect" deriving from ק־ף – √q-p "bend, arch, lean towards" and similar verbs fit into the shaCCéC verb-pattern.
For example, the abstract quadriliteral root t-r-g-m / t-r-j-m gives rise to the verb forms תרגם tirgem in Hebrew, ترجم tarjama in Arabic, ተረጐመ täräggwämä in Amharic, all meaning "he translated".
[7] However, in modern Israeli Hebrew, syllables are allowed to begin with a sequence of two consonants (a relaxation of the situation in early Semitic, where only one consonant was allowed), which has opened the door for a very small set of loan words to manifest apparent five root-consonant forms, such as טלגרף tilgref "he telegraphed".
[13] Unlike the Hebrew examples, these roots conjugate in a manner more like regular verbs, producing no indivisible clusters.