What is the meaning of Past_anterior?

A compound tense used in literary French, Spanish, Portuguese and Italian, in function a pluperfect, and in form composed of the conjunction of the simple past tense of an auxiliary verb (avoir, être) with the past participle. Example: Après que la femme et l'homme l'eurent remercié = After the woman and the man had thanked him

Source: wiktionary.org