The word pharaoh stems from per-aä, which literally means the big house, i.e. the palace.
The special pharaoh powers meant that it was dangerous to touch him: he was as it were magically electrified. Still the pharaoh was no real god - worshipping him was highly unusual and did occur rarely. In this light pharaohs have been compared with the typically African kings and rainmakers.
Indeed the Egyptians were convinced that world order and the country's welfare depended on his physical strength. The pharaoh was responsible for the yearly inundation of the Nile, the suppression of dark and chaotic forces and the defeat of all of Egypt's enemies. This explains why at his accession of the throne, the pharaoh had to do a physical test to prove his fitness. This endurance run had to be repeated periodically, which coincided with the sed-feast. In later dynasties this test was a formality, but it is generally considered very well possible that old and weak kings were killed in prehistoric times.