Grammatical mood

Because modern English does not have all of the moods described below, and has a very simplified system of verb inflection as well, it is not straightforward to explain the moods in English. (The English moods are indicative, subjunctive, and imperative). Note, too, that the exact sense of each mood differs from language to language.

Grammatical mood per se is not the same thing as grammatical tense or grammatical aspect, although these concepts are conflated to some degree in many languages, including English and most other modern Indo-European languages, insofar as the same word patterns are used to express more than one of these concepts at the same time.

Currently identified moods include conditional, imperative, indicative, injunctive, negative, optative, potential, subjunctive, and more. Infinitive is a category apart from all these finite forms, and so are gerunds and participles. Some Uralic Samoyedic languages have over ten moods; Nenets has as many as sixteen. The original Indo-European inventory of moods was indicative, subjunctive, optative, and imperative. Not every Indo-European language has each of these moods, but the most conservative ones such as Avestan, Ancient Greek, and Sanskrit have them all.

It should be noted that not all of the moods listed below are clearly conceptually distinct. Individual terminology varies from language to language, and the coverage of (e.g.) the "conditional" mood in one language may largely overlap with that of the "hypothetical" or "potential" mood in another. Even when two different moods exist in the same language, their respective usages may blur, or may be defined by syntactic rather than semantic criteria. For example, the subjunctive and optative moods in Ancient Greek alternate syntactically in many subordinate clauses, depending on the tense of the main verb. The usage of the indicative, subjunctive and jussive moods in Classical Arabic is almost completely controlled by syntactic context; the only possible alternation in the same context is between indicative and jussive following the negative particle lā.