Many bases can be used at will as nouns, as adjectives, and as verbs. Thus the Tamil _kadu_ can mean "sharpness," "sharp," and "to be sharp." Other bases are of course more restricted in their respective spheres. The inflection of words is effected by agglutination, i.e. various additions are suffixed to the base in order to form what we would call cases and tenses. Such additions have probably once been separate words. Most of them are, however, now only used as suffixes. Thus from the Tamil base _k[=o]n_, "king," we can form an accusative _k[=o]n-ei_, a verb _k[=o]n-en_, "I am king," and so on. Dravidian nouns are divided into two classes, which Tamil grammarians called high-caste and casteless respectively. The former includes those nouns which denote beings endowed with reason, the latter all others. Gender is only distinguished in the former class, while all casteless nouns are neuter. The gender of animals (which are irrational) must accordingly be distinguished by using different words for the male and the female, or else by adding words meaning male, female, respectively, to the name of the animal--processes which do not, strictly speaking, fall under the head of grammar. There are two numbers, the singular and the plural. The latter is formed by adding suffixes. It, however, often remains unmarked in the case of casteless nouns. Cases are formed by adding postpositions and suffixes, usually to a modified form of the noun which is commonly called the oblique base. Thus we have the Tamil _maram_, "tree"; _maratt-[=a]l_, "from a tree"; _maratt-u-kku_, "to a tree"; _v[=i]du_, "a house"; _v[=i]t[t.]-[=a]l_, "from a house." The case terminations are the same in the singular and in the plural. The genitive, which precedes the governing noun, is often identical with the oblique base, or else it is formed by adding suffixes. The numeral system is decimal and higher numbers are counted in tens; thus Tamil _pattu_, "ten"; _iru-badu_, "two tens," "twenty." The personal pronoun of the first person in most dialects has a double form in the plural, one including and the other excluding the person addressed. Thus, Tamil _n[=a]m_, "we," i.e. I and you; _n[=a]ngal_, "we," i.e. I and they.