The roots of verbs and most nouns in the Semitic languages are characterized as a sequence of consonants or "" (hence the term consonantal root). Such abstract consonantal roots are used in the formation of actual words by adding the vowels and non-root consonants (or "transfixes") which go with a particular morphological category around the root consonants, in an appropriate way, generally following specific patterns. 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).