Arabic, like the other so-called Semitic languages, is totally different in construction from European tongues.
Every word in the language is referred to a root, which consists of three radical letters. Roots of two, or four or more radicals do exist, but they need not be noticed, since they are treated in practice as though they were derived forms.
Instead of modifying a root to express a modified idea by prefixing or affixing syllbles, the Arabic treats the three radicals as algebraists treat the symbols x, y, z, and express ideas by formulæ arrived at by combining these with certain other letters, called by European grammarians "servile," but by the natives زائدة zùïdah, "pleonastic". The letters so used are contained in the words أمان و (Arabic characters)