It's on the tip of my tongue. - 생각이 날 듯 말 듯 하다.

It's on the tip of my tongue.

I know the word/name etc., but I can’t remember it right now.

알고 있는 건데, 생각이 안나!!!

"생각이 날 듯 말 듯 하다."의 의미

1. 

You're sure you know it but can't quite get it. Then you can say, "it's right on the tip of my tongue!".

2. 

I know his name, but I just can’t remember it for some reason. It’s right on the the tip of my tongue.

3. 

I know the answer, wait just a moment. It’s right on the tip of my tongue.