什么意思用英语怎么说

1.这是什么意思？    
What's the meaning of this?

2.你这是什么意思?    
What do you mean?

3.你到底是什么意思?    
What on earth do you mean?

4.我不懂这个词是什么意思。    
I don't understand what the word means.

5.我不明白他说的什么意思。    
I couldn't make out what he was saying。

6. 我真不知道他这是什么意思。    
I really don't know what he meant by that.