is "donderdag" pronounced "Tonder-dag?"
Thor is the God of Thunder - and Thursday is "Thor's Day" (At least in English), it was named after him. If it is pronounced "Tonderdag" it will be easier to remember (because of Tonder/ Thunder).
Donderdag has the same origin, it is actually pronounced with a d, not a t (might not be too clear a difference for a non-native ear). But you can definitely use your mnemonic:
- zon = sun
- zondag = Sunday
- donder = thunder
- donderdag = hmmm… ;)
- maan = moon
- maandag = hmmm… ;)
- vrij = free
- vrijdag = hmmm… ;)
Vrijdag actually was named after the goddess Freyja, but nothing stops you from thinking of Friday as free day or make love day in Dutch. :) Also in Dutch Thor is Donar, that name and donder are related.