Why is "Good Night!" dismissive
To start off let us construct a situation were I am walking along and I pass another person. Depending on the time of day and to be polite I say one of the following:
- "Good Morning!"
- "Good Evening!"
- "Good Night!"
- "Good Day!"
Now 1 and 2 are common welcoming and polite gestures and I have no problem with their use. However the problem lies with 3: Why is it so dismissive compared with 1 and 2?
If I said "Good Night!" to somebody when walking at around 11 p.m why does it sound like I am putting them to bed?
Finally as a related matter, why is 4 not used too often? In other languages 4 seems to be more common then an equivalent "Hello!" and sometimes 4 and "Hello!" posses the same.meaning.
In American English, "good morning," "good afternoon," and "good evening" are all commonly used as greetings.
"Good day," by contrast, can actually be used fairly dismissively in its own right, especially if there is a name or title following it: "Good day, madame!" or, more famously, "Good day, sir!"
"Good night," on the other hand, tends to be used as a farewell rather than a greeting. To some extent, I suspect this is a psychological matter: even though we often use "night" as a substitute for "evening," I think in general we associate "night" with much later times than "evening," where we're not normally expecting to have company. Therefore, using "good night" in that manner seems unnatural.
It's the same principle in other languages, such as French and German. You'd use "Bonsoir" or "Guten Abend" as a greeting, but not "Bonne nuit" or "Gute Nacht."
All of those can be a greeting or a dismissal, depending on how you enunciate.
"Good xxxx!" is a perfectly acceptable way to hail an acquaintance, and can also be used to dismiss someone you don't wish to speak to any more.
"Good night!" is a less common greeting than the others, but still acceptable.