1. the study or a course of study of history before the end of the Western Roman Empire A.D. 476.
2. information or an event of the recent past that is common knowledge or is no longer pertinent: Last week's news is ancient history.
3. an event, as in a person's life, that occurred in the remote past and has no practical relationship with the present: She was my best friend in high school, but that's ancient history now.
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