In grammar, tense is a category that locates a situation in time, to indicate when the situation takes place.[1][note 1] Tense is the grammaticalisation of time reference, and in general is understood to have the three delimitations of "before now", i.e. the past; "now", i.e. the present; and "after now", i.e. the future. The "unmarked" reference for tense is the temporal distance from the time of utterance, the "here-and-now", this being absolute-tense. Relative-tense indicates temporal distance from a point of time established in the discourse that is not the present, i.e. reference to a point in the past or future, such as the future-in-future, or the future of the future (at some time in the future after the reference point, which is in the future) and future-in-past or future of the past (at some time after a point in the past, with the reference point being a point in the past). Not all languages grammaticalise tense, and those that do differ in their grammaticalisation thereof. Not all grammaticalise the three-way system of past–present–future. For example, two-tense languages such as English and Japanese express past and non-past, this latter covering both present and future in one verb form. Four-tense languages make finer distinctions either in the past (e.g. remote vs recent past), or the future (e.g. near vs remote future). The six-tense language Kalaw Lagaw Ya of Australia has the remote past, the recent past, the today past, the present, the today/near future and the remote future. The differences between such finer distinctions are the distance on the timeline between the temporal reference points from the present.

Etymology Tense comes from Old French tens "time" (now spelled temps through deliberate archaisation), from Latin tempus "time".[2] The adjective "tense" is unrelated, being a Latin loan from tensus, the perfect passive participle of tendere "stretch".[3] [edit]Tense marking Tense is normally indicated by a verb form, either on the main verb or on an auxiliary verb. The tense markers are normally affixes, but also stem modification such as ablaut or reduplication can express tense reference, and in some languages tense can be shown by clitics. Often combinations of these can interact, such as in Irish, where there is a proclitic past tense marker do (various surface forms) used in conjunction with the affixed or ablaut-modified past tense form of the verb. Languages that do not have grammatical tense, such as Chinese, express time reference through adverbials, time phrases, and so on. [edit]Other uses of the term "Tense" : Tense, aspect, and mood In many language descriptions, particularly those of traditional European linguistics, the term tense is erroneously used to refer to categories that do not have time reference as their prototypical use, but rather are grammaticalisations of mood/modality (e.g. uncertainty, possibility, evidentiality) or aspect (e.g. frequency, completion, duration). Tense differs from aspect in showing the time reference, while aspect shows how the action/state is "envisaged" or "seen" as happening/occurring. The most common aspectual distinction in languages of the world is that between perfective (complete, permanent, simple, etc.) and imperfective (incomplete, temporary, continuous, etc.). The term tense is therefore at times used in language descriptions to represent any combination of tense proper, aspect, and mood, as many languages include more than one such reference in portmanteau TAM (tense–aspect–mood) affixes or verb forms. Conversely, languages that grammaticalise aspect can have tense as a secondary use of an aspect. In many languages, such as the Latin, Celtic and Slavic languages, a verb may be inflected for both tense and aspect together, as in the passe compose/passe simple (historique) and imparfait of French. Verbs can also be marked for both mood and tense together, such as the present subjunctive (So be it) and the past subjuncitve (Were it so), or all three, such as the past perfect subjunctive (Had it been so). The word tempus was used in the grammar of Latin to describe the six "tenses" of Latin. Four are absolute tenses, of which two are combined tense–aspect categories, marking aspect in the past, while two are relative tenses, in showing time reference to another point of time: Praesens (= present) Praeteritum imperfectum (= imperfective past, i.e. a combined tense–aspect) Praeteritum perfectum (= perfective past, i.e. a combined tense–aspect) Futurus (= future) Plus quam perfectum (= relative past, i.e. a past that refers to the past of a reference in the past) Anterior Futurus (= relative future, i.e. a past that refers to the past of a future point) The tenses of Ancient Greek are similar, though having a three-way aspect contrast in the past, the aorist, the perfect and the imperfect. The aorist was the simple past which contrasted with the imperfective (uncompleted action in the past) and the perfect, the past form that had relevance to the present. The study of modern languages has been greatly influenced by the grammar of these languages, seeing that the early grammarians, often monks, had no other reference point to describe their language. Latin terminology is often used to describe modern languages, at times erroneously, as in the application of the term "pluperfect" to the English "past perfect", the application of "perfect" to what in English more often than not is not "perfective", or where the German simple and perfect pasts are called respectively "Imperfektum" and "Perfektum", despite the fact that neither has any real relationship to the aspects implied by the use of the Latin terms.