Well, you are kinda right. The meaning "maiden" evolved later. The reason is because a woman would lose her virginity only when she would be married. This is the general rule of course, since there were prostitutes too. Nevertheless, the actual meaning of the word is virgin,more enforced by Virgin Mary, "Maria hē Parthenos".
*Excuse my latinizations; my mobile doesn't support Greek.
Sanest choice in this insane world; Beware the beast but enjoy the feast he offers... ~T. Holopainen