Perfect Aspect (definition)
Perfect verbs are types of verbs that refer to a contrast in time or duration. Perfect aspect is a situation seen as a whole regardless of time contrast which may be part of.
A sentence marked for perfect aspect conveys the meaning of a state in the time conveyed by the tense that is 'due [exclusively] to' a past action. The aspect occurs in all three tenses. In Scottish Gaelic, perfect aspect is marked by the particle 'air', which is homophonous and homographic with the preposition meaning 'on'.
See Also
After-Perfect Aspect Prospective Aspect
External Links
http://en.wikipedia.org/wiki/Perfect_aspect
http://www.statemaster.com/encyclopedia/Perfect-aspect
References
Crystal, David. A Dictionary of Linguistics and Phonetics. The language library. Oxford, UK: Blackwell, 1997.