good day

英 [ˌɡʊd ˈdeɪ]

美 [ˌɡʊd ˈdeɪ]

int. (白天见面或分手时用语)白天好，你(们)好，再见

牛津词典

exclamation

（白天见面或分手时用语）白天好，你（们）好，再见
used to say hello or goodbye politely when people first see each other or leave each other during the day
1. Good day to you.
  你好。

CONVENTION （问候用语，代替Hello及Goodbye）你（们）好，再见
People sometimes say 'Good day' instead of 'Hello' or 'Goodbye'.
1. Well, I'd better be off. Good day to you.
  好啦，我得走了，再见。

noun

You could say it was a doggone good day for this golden retriever in Washington State.
你可能会说，对这只华盛顿的金毛猎犬真是糟糕的一天，昨天晚上它坐的汽车翻到了沼泽地上。
Tell me about a good day.
和我说说那些美好的日子。
Have a good day.
有一个早晨好。
Today is a good day, the rain stopped;
今天是个好日子，大雨停了；
The three friends have a good day.
这三个朋友度过了愉快的一天。
But you said it wasn't a good day.
但你说今天不是个好日子。
Good day to you, Bernard! It's a positive delight to see you
你好，伯纳德！见到你真高兴。
Today was a good day and a bad day.
今天是一个好日子，也是一个坏日子。
It's a good day for playing practical jokes on your friends.
这是一个对你的朋友们开实际玩笑的好日子。
I'm sorry to complain so much. It's just not a good day.
我很抱歉发了这么多牢骚。今天可不是个好日子。