The female version of a metrosexual. Where a metrosexual is a predominately straight male who comes across more as a homosexual a femetrosexual is a mostly straight girl who presents like a lesbian.

Basically if -

metrosexual = faggy straight boy
then
femetrosexual = dykie straight girl

The term goes beyond tomboy which would be one type of femetrosexual.

The term could easily be used to describe a bi girl who comes across as a lesbian.