Raidhoo stands for travelling

Runes are ancient alphabet used by germanic peoples which Norwegians belong to. One of runes which has been very widely used by Norwegian vikings is rune known as Raidhō (ō is pronounced as long sound of o), which actually means riding, travelling, taking action, moving forward. Raidhō is the rune of the sun, pictured in the Norwegian imagination as a mighty cartwheel rolling across the sky.

Thus this rune has become connected with carts and land transportation in general. The visual representation of the Raidhō rune is a letter similar to capital R.