Greek, like all of the older Indo-European languages, is highly inflected. It is highly archaic in its preservation of Proto-Indo-European forms. In ancient Greek, nouns (including proper nouns) have five cases (nominative, genitive, dative, accusative, and vocative), three genders (masculine, feminine, and neuter), and three numbers (singular, dual, and plural). Verbs have four moods (indicative, imperative, subjunctive, and optative) and three voices (active, middle, and passive), as well as three persons (first, second, and third) and various other forms. Verbs are conjugated through seven combinations of tenses and aspect (generally simply called "tenses"): the present, future, and imperfect are imperfective in aspect; the aorist (perfective aspect); a present perfect, pluperfect and future perfect. Most tenses display all four moods and three voices, although there is no future subjunctive or imperative. Also, there is no imperfect subjunctive, optative or imperative. The infinitives and participles correspond to the finite combinations of tense, aspect, and voice.