Hi. Hello. How are you?

All perfectly good ways to greet someone. As are…

Good morning. Good afternoon. Good evening. And good ni…

Oh wait. No.

Good morning, afternoon, and evening all mean hello, but good night only means goodbye. Why is that?

The simplest explanation is that we’re more likely to be saying goodbye to someone than hello at night (and we’re probably most likely to say hello in the morning, which is why good morning‘s by far the most common of the other three expressions).

Of course if we’re going out at night, we’ll probably say hello to somebody, but if we were to use an expression with good, we’d say good evening (though we’d actually say hi or hello, as good evening is so formal).

Because, what’s the difference between evening and night anyway? We all have a general sense of the difference between the two, with total darkness usually being an indicator of nighttime.

But the difference is more than just degrees of light, or specific times (when I was a more literal-minded young chap, evening was between 5 and 9pm, and night was from 9pm to some point before I woke up). If we’re still active, it feels more like evening, whereas nighttime is when we’re generally asleep.

And who’s going to say hello, let alone good night, when they’re asleep!?