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".