One of the readers of the DWOTD asked us the following:
Which version is correct: “Prettig weekend!” or “Prettige weekend!”
One says “prettig weekend” because it’s derived from “Ik wens je een prettig weekend” (“I wish you a nice weekend”).
See Declining adjectives for more information.
Another valid question would be:
Why do we use the English word “weekend” instead of the Dutch “weekeinde”?
Although the use of English words in the Dutch language is quite common, the frequent use of “weekend” has led this word to become an official part of the Dutch language.
The Dutch equivalent “weekeinde” is used in more formal communications, although the use of “weekend” in such communications would not be incorrect.