the Berasit Hebrew Dictionary

In many semitic languages, and particularly in ancient Hebrew, the roots of verbs and most nouns are characterized as a sequence of consonants. Although some biconsonantal and quadriconsonantal roots do occur, the large majority of words are formed by triconsonantal roots; that is, a series of three consonants.¹⁾

Arranging three digits of the 18 Hebrew consonants²⁾ yields 5832 possible roots which form the essential vocabulary. Not all of these combinations are used however.