femme fa·tale 
(fĕm′ fə-tăl, -täl, făm′)
(fĕm′ fə-tăl, -täl, făm′)n. pl. femmes fa·tales (fĕm′ fə-tăl, -tălz, -täl, -tälz, făm′)
An alluring and seductive woman, especially one who leads men into compromising and dangerous situations.
[French : femme, woman + fatale, deadly.]