A large thing or person is greater in size than usual or average.

A large amount or number of people or things is more than the average amount or number.

A large organization or business does a lot of work or commercial activity and employs a lot of people.

Large is used to indicate that a problem or issue which is being discussed is very important or serious.

You use at large to indicate that you are talking in a general way about most of the people mentioned.

If you say that a dangerous person, thing, or animal is at large, you mean that they have not been captured or made safe.

You use by and large to indicate that a statement is mostly but not completely true.