Five Faces

Gayathri is described as having five faces, Five Faces Goddess.

1. The first is “Aum”.
2. The second is “Bhoor bhuvas svah”. 
3. The third is “Thathsavithur Varenyam”.
4. The fourth is “Bhargo Devasya Dheemahie”. 
5. The fifth is”Dheeyo yo nah prachoedaaath”. Gayathri represents in these five faces the five Pranas(life forces).

http://www.sripanchamukhagayatri.org/