From the Glossary of The Wheel of Time

In the Old Tongue, "Maidens of the Spear." One of a number of warrior societies of the Aiel; unlike any of the others, it admits women and only women. A Maiden may not marry and remain in the society, nor may she fight while carrying a child. Any child born to a Maiden is given to another woman to raise, in such a way that no-one knows who the child's mother was. ("You may belong to no man, nor may any man belong to you, nor any child. The spear is your lover, your child, and your life.") These children are treasured, for it is prophesized that a child born of a Maiden will unite the clans and return the Aiel to the greatness they knew during the Age of Legends.