The 'lør' element was formed as part of the phrase 'Laugôz dagaz' but the independent noun 'laugô' became 'laug' in Norwegian which is now quite a dated word compared to 'bad' (bath). It is apparently cognate with English 'lye' which has a different meaning but same root. It's also related to 'lave' (from Latin 'lauere') ultimately from a common source to the Germanic. If you think of it as 'lyeday' or 'laveday', you wouldn't be completely correct but may give some context to help remember it. The difference of stress for the development of compounds and individual words can also seen in 'Odin' and 'Onsdag'.