I’ve gotten a few questions about what, precisely, vaettir are and if the are the same as Greek nymphs.
Let’s start with the word itself. Vaettr (pl. Vaettir, sometimes rendered as wights, vetter, or väsen depending on the language and location) is etymologically related to the verb to be (ON vera). The word can be translated as “beings”, usually with the connotation that we’re talking about supernatural beings or spirits of some sort, and there are many types of vaettir.
Landvaettir are the closest to the Greek nymphs (as far as I can tell) in that they are tied to particular locations or natural objects. Housevaettir are spirits that appear in and around the home and interact with humans (such as the nisse, haugbonde, kobolds, etc. The concept is very similar to the Scottish and English folklore about brownies). Alfar and Duergar are also vaettir, Jotnar are vaettir, the spirits of the dead can count as vaettir, and even the Gods can be considered vaettir. Generally speaking, however, vaettir refers to “lesser” spirits, not Deities.
Vaettir are also not exchangeable with the Irish sidhe or other Irish and Gaelic fairies. They have some things in common with the alfar, but there are some cultural differences and the customs and behaviors one needs to obey to stay safe are not always the same. Even the mound-alfar (the dead in their howes), when there was cultural exchange with the Irish, were not translated as sidhe because it was understood that they were different spirits altogether. The Irish translated them as alcaille, “ghost of the dead”. (de Vries, Jan. Altnordisches etymologisches Wörterbuch, 2nd Ed. p.6)
There are too many types of vaettir for me to outline them all in one post, so I’m going to try to put together an informational series giving information about different specific vaettir types. In general, it’s worth knowing that turning down food and drink from Scandinavian vaettir is dangerous because it insults them (the opposite of Irish/Gaelic advice about fairy consumables), with the exception of troll drink (which can burn human flesh). Humans seem to have interacted with vaettir on a more regular basis than they did with the Gods, in the same way that you interact with your next door neighbors far more than you do with the mayor or the politicians representing you in the government.