The pluperfect is a type of verb form, traditionally treated as one of the tenses of certain languages, used in referring to something that occurred earlier than the time being considered, when the time being considered is already in the past. The meaning of the pluperfect is equivalent to that of English verb forms such as `(we) had arrived` or..... Found on http://en.wikipedia.org/wiki/Pluperfect
• (a.) More than perfect; past perfect; -- said of the tense which denotes that an action or event was completed at or before the time of another past action or event. • (n.) The pluperfect tense; also, a verb in the pluperfect tense. Found on http://thinkexist.com/dictionary/meaning/pluperfect/
Plu'per`fect adjective [ Latin plus more + perfectus perfect; confer French plus-que-parfait , Latin plusquamperfectum .] More than perfect; past perfect; -- said of the tense which denotes that an action or event was completed at or before the time of another past action or ... Found on http://www.encyclo.co.uk/webster/P/111
A form of verbs found in many Indo-European languages and which expresses an action which is in the remote past; those languages which possess such a tense also have a simple tense which is understood to refer to a time closer to the present. Found on https://www.uni-due.de/ELE/LinguisticGlossary.html