Moin is a
Frisian language greeting from East
Frisia, the eastern Netherlands, North Frisia and Flensburg, meaning hello.
The word derives from the Frisian word
mooi, meaning beautiful. The first
moin is different from the second, it is mooi (
frisian=good, beautiful), the second moin, also morn means "day" in Frisian language. Similar forms in Low saxon are mooien Dag, mooien
Abend, mooien Mor(g)en. Moin is semantically equivalent to the low saxon
greeting Tag. and replaced it in many areas Therefore, Moin can be used 24 hours a day. The duplication Moin Moin is used as emphasis and for a more polite form as well. In Southern Jutish, Moin is used for hello and good bye, but Moin Moin is solely used for good bye. Moin moin literally means "(Have a) good day".
Normally "Moin" is the same as "good". If you meet a person ask "good? (Moin!)" and the answer is "good!good! (Moin! Moin!)"
People in more southern parts of Germany often mistakenly assume that Moin is a short from of
Morgen (meaning "morning") and should be used like "good morning".