1. The adoption of the dress, mannerisms, or social role of the opposite sex; cross-dressing or gender nonconformity.
Usage: dated; medical/historical term; named after the Chevalier d'Éon, an 18th-century French diplomat

Examples

• The term eonism was coined in the 19th century to describe gender-nonconforming behavior.
• Historical accounts of eonism in various cultures reveal diverse attitudes toward gender expression.
• Early medical literature used eonism as a clinical descriptor, though the term is now considered outdated.
• The Chevalier d'Éon's life inspired the coinage of the word eonism in academic circles.