that3 S1 W2 [+ adjective/adverb]
used to say how big, how much etc, especially when you are showing the size, amount etc with your hands:
It was quite a large fish - about that long.
He missed hitting the car in front by that much.
2 [usually in negatives] spoken
as much as in the present situation or as much as has been stated:
I'm sorry, I hadn't realized the situation was that bad.
No one expected it to cost that much.
The advanced exam is more difficult, but not many students progress that far.
used to mean fairly short, only a few etc:
Will's not that tall, considering he's 16.
The film wasn't all that good.
4 British English spoken informal
used to emphasize how big, bad, much etc something is:
I was that embarrassed I didn't know what to say.