1. History of humankind in the period before recorded history.
2. The circumstances or developments leading up to or surrounding a situation, event, or development; background: "[He] then told me the curious prehistory of his obsessive interest in the seduction theory" (Janet Malcolm).

The American Heritage® Dictionary of the English Language, Fourth Edition Copyright © 2007, 2000 by Houghton Mifflin Company. Updated in 2009. Published by Houghton Mifflin Company. All rights reserved.