
It's proof of CONCEPT.
The Big Bang Theory Season 9, Episode 24

Do you understand
the CONCEPT of blackmail?
The Big Bang Theory Season 1, Episode 16

with the CONCEPT
that time is an illusion.
The Big Bang Theory Season 12, Episode 19

There's an economic CONCEPT
known as a "positional good"...
The Big Bang Theory Season 3, Episode 15

I didn't really understand
the CONCEPT of death, the finality of it.
Game of Thrones Season 2, Episode 9