In grammar, tense is a category that locates a situation in time, to indicate when the situation takes place. Tense is the grammaticalisation of time reference, often using three basic categories 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. Languages without tense are called tenseless languages and include Burmese, Dyirbal and Chinese. Not all grammaticalise the three-way system of past–present–future. For example, some two-tense languages such as English and Japanese express past and non-past, this latter covering both present and future in one verb form, whereas others such as Greenlandic and Quechua have future and non-future. 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.
In linguistics, a stem is a part of a word. The term is used with slightly different meanings.
In one usage, a stem is a form to which affixes can be attached. Thus, in this usage, the English word friendships contains the stem friend, to which the derivational suffix -ship is attached to form a new stem friendship, to which the inflectional suffix -s is attached. In a variant of this usage, the root of the word (in the example, friend) is not counted as a stem.
Spanish verbs are a complex area of Spanish grammar, with many combinations of tenses, aspects and moods (up to fifty conjugated forms per verb). While conjugation rules are relatively straightforward, a large number of verbs are irregular. Among these, some fall into more-or-less defined deviant patterns, while others are uniquely irregular. This article tries to summarize the common irregular patterns.
As in all Romance languages, many irregularities in Spanish verbs can be retraced to Latin grammar.
Spanish verbs are one of the more complex areas of Spanish grammar. Spanish is a relatively synthetic language with a moderate to high degree of inflection, which shows up mostly in Spanish verb conjugation.
As is typical of verbs in virtually all languages, Spanish verbs express an action or a state of being of a given subject, and like verbs in most of the Indo-European languages, Spanish verbs undergo inflection according to the following categories: