Orientation toward the Sun was very important for the Vikings which
is seen when the dead are always placed with his face in the same
direction at burials. When we look at what their weather-mark names
indicates, we see that Sunrise was important as it was from this
orientation, the other was expressed.
East (oirthear) means against the horizon (Sunrise),
West (iarthair) means backward,
North (tuaisceart) is to the left,
South (deisceart) is to the right all direction when they facing
sunrise.
When we then look at the words is a certain connection between the
words oirthear, orient and the Latin o’riens. The Latin word
o’riens means uprising (the Sun). And the Vikings came in
contact with the Romans in Britain, so it is not impossible that
their words came from there also.
Then You could try to find the other three sides also.
tuaisceart, iarthair, deisceart.