Diminutive of Frances, from Latin 'Franciscus' meaning free one or from France.
Fanny began its long life as an affectionate diminutive of Frances — and through Frances, it traces back to the Latin Franciscus, meaning "Frenchman" or "free one," the name made famous by Saint Francis of Assisi. In the eighteenth and nineteenth centuries, Fanny was a thoroughly respectable and widely beloved name throughout Britain and America, carried with complete dignity by remarkable women who shaped their respective fields. Fanny Burney, the eighteenth-century English novelist and diarist, pioneered the novel of manners and influenced Jane Austen directly.
Fanny Mendelssohn, sister of Felix, was a brilliant composer whose work was suppressed largely by virtue of her gender; she has been reclaimed in recent decades as one of the overlooked geniuses of the Romantic era. Jane Austen herself gave the name to Fanny Price, the quiet, principled heroine of Mansfield Park — a character whose moral clarity was intended as a tribute to the name's associations with steadfastness and inner strength. D.
Salinger's Glass family stories, appearing in the novella Franny and Zooey (spelled with an 'r,' but sharing the same root affection). In the twentieth century, the name underwent a complicated transformation in British English, where "fanny" acquired a vulgar slang meaning that effectively suppressed the name's use in the UK for several generations. In American English, where the slang meaning is far milder, Fanny has begun a quiet revival among parents drawn to vintage names with genuine historical pedigree. It is a name with a remarkable biography — from saint to satirist, from composer to novelist — and its return feels like a small act of cultural restoration.