It can be used to describe something related to Reykjavik, such as:
* Reykjavíkan culture: referring to the culture of the city of Reykjavik.
* Reykjavíkan cuisine: referring to the food of Reykjavik.
* Reykjavíkan architecture: referring to the architecture of Reykjavik.
It can also be used to describe a person from Reykjavik, like a Reykjavíkan resident.