late 14c., "deprive (a maiden) of her virginity," also "excerpt the best parts of (a book)," from Old French desflorer (13c., Modern French déflorer) "to deflower (a garden); to take the virginity of," from Late Latin deflorare, from de- (see de-) + flos "flower" (see flora). Notion is "to strip of flowers," hence "to ravish," which is the oldest sense in English.
The French Indians are said not to have deflowered any of our young women they captivated. [James Adair, "The Life of an Indian Trader," London, 1775]