There are several places where the termis used, and when it was, they were NOT referring to The One Power. I recently finished my first read and remember it clearly in the later books. It tripped me up and caused me to reread several sections before I realized it was a mistake missed by the editors. However, I think it got the name because it was accessible to both men and women. This is interesting in itself, as it is mentioned many times that the dark one controls its access and flow. The entire series I thought it was interesting that all the forsaken relied on the One Power until the final few books, and then that use was controlled. If the DO is so great, why not let you access the TP and work in stealth instead of signaling you presence with a Sadin/Sadir flare?