An attractive woman who is, for one reason or another, dangerous. French for “fatal woman,” the term has been used in English since about 1900, and today it is often used more ironically than seriously. Michael Arlen used it in The Green Hat (1924): “So you heard about it from that femme fatale, did you?” Much more recently Richard Dyer used it in the sense of “very glamorous” in describing the singer who played the leading role in the opera Carmen: “She’s physically and vocally limber, and revels in her femme-fatale look” (Boston Globe, March 24, 2005).