Like last week, your business partner takes you in an elevator to the meeting room, but this time you are up north, maybe in Kiel. It’s 6 pm. Somebody steps in, looks at you, and says “Moin!” Did that person oversleep and wish “good morning” at the end of the day?
Certainly not! Northern Germans use “Moin!” as a typical local greeting all day long. Your immediate guess will be that it is the regional version of “morning”. Maybe, maybe not. What does it mean and where does it come from?
The etymology of “moin” is uncertain. The connection to the standard German word “Morgen” (morning) seems natural, but is debated. Using “Guten Moin!” as a term for “Good morning!” for example would not be seen as correct and create raised eyebrows with any North German. Probably, “Moin!” comes from the East Frisian word “mōi” respectively from the Middle Low German “moi(e)”, which both mean “good/nice/lovely”. In East Friesland, they also say “Moin Dag!” corresponding to a Standard German “Guten Tag!” (“good day!”). So in this case, the best translation for today’s “Moin!” would be “Have a good one!” People in other parts of the country might use “Moin!” as well, but not during the whole day.
Frequently, you hear the reduplication “Moin-Moin!”. This expression is deemed to be more polite and can especially be used in response to the single “Moin!” Some people regard this as overdoing, though. “Moin-Moin!” might be derived from the Frisian phrase “Moi Morn!” (“Good morning!”), but it is no longer limited to the morning: Just like the simple term, North Germans (and some Danish and Dutch as well) use it throughout the day.
“Moin” continues its success across the country, and even entered the lingo of young Germans: “Moinsen!” is a modification of “Moin!”, and a very casual greeting among youths.
Although the expression originated at the North Sea coast, the oldest mention can be traced back to 1828, where “Moin!” and “Moin-Moin!” emerge as a greeting among officers in the “Berliner Conversations-Blatt für Poesie, Literatur und Kritik”.
The German Navy allows “Moin!” as a semiformal salutation. According to sailors, this greeting promotes a less formal atmosphere and a spirit of comradeship.
So, using “Moin!” as a greeting is a good idea in Northern Germany, and across the border in Southern Denmark and the Eastern Netherlands. It will not be understood in Southern Germany, unless you happen to talk to somebody who served in the navy.