Definition
Used to describe a situation where you are sure you know something and feel very close to remembering it, typically a word or name.
I know the actor's name; it's right on the tip of my tongue, but I can't quite recall it at the moment.
I'm quite sure I've learned this word before; it's on the tip of my tongue.
The advice I wanted to give you is on the tip of my tongue, let me think for a second.