Why, to me the very word 'numbers' suggests only a vague and troublesome concept.

The lost time was suddenly sitting on him like a load of bricks - a real thing, not just a vague concept.

To begin with, that is a very vague concept.

If only it could give me more than vague concepts.

It is in just the form of such a vague concept that the message comes to me.

How, then, can your vague concepts, which are against this natural order, stand up to the truth?

I think, but I'm not sure, that they had some vague concept of reincarnation.

He wasn't certain, for at first he'd had but a vague concept of time.

After a hundred tries, though, he still had only the most vague concept of what should happen in between.

Political culture is a vague abstract concept that has been subject to various definitions.