Fitna or Fitnah(n)(this is the right pronounciation) is an arabic word it is the infinitive of Fatana(v) which means (change and made up the thing to make it look pretty to make someone loves it) .
in jewelry: like if someone got a useless piece of jewelry, added to it cheap stones, but made it (look amazing) and sold it for more than what it deserves, then he fatana the customer. the piece looks precious and u can be proud of wearing it more than other more expensive similar piece, but in fact it's a fitna, or something makes u love it but the deep value of it isn't real.
Fitna is working in politics when someone cheats someone else with beautiful words to make him achieve something harmful for him.
the very beautiful women whom are attracting men to do a certain something with invincible attraction are Fitna
well. all the women are attractive, so all the women if a man isn't in a realtionship and satisfied are FITNA . this is my personal idea about the women. the man usually waste alot of time in thinking and caring about women. i hope i'm not, but i am. LOL. the women are the Fitna which i can't avoid then.
we are considered to not allow the Fitna to affect us. we say sometimes to pray "god please Don't make it Fitnah to us" or as mskk2008 said "May Allah does not make it (the hardship) Fitnah for us", when we feel we're weak to resist a certain attractive thing could be harmful but loved (and this is the source of the test in the word Fitnah)
so the test isn't in the fitna, but to not behave according to the fitna, and the fitna is usually very strong to get avoided)