Tense, aspect, and mood

The distinction between grammatical tense, aspect, and mood is fuzzy and at times controversial. The English continuous temporal constructions express an aspect as well as a tense, and some therefore consider that aspect to be separate from tense in English. In Spanish the traditional verb tenses are also combinations of aspectual and temporal information.

Going even further, there's an ongoing dispute among modern English grammarians (see English grammar) regarding whether tense can only refer to inflected forms. In Germanic languages there are very few tenses (often only two) formed strictly by inflection, and one school contends that all complex or periphrastic time-formations are aspects rather than tenses.

The abbreviation TAM, T/A/M or TMA is sometimes found when dealing with verbal morphemes that combine tense, aspect and mood information.

In some languages, tense and other TAM information may be marked on a noun, rather than a verb. This is called nominal TAM.
http://en.wikipedia.org/wiki/Grammatical_tense