0 to take the items you have bought, esp. in a large food store, to an area where you pay for them: --
I had already checked out when I remembered that we were out of milk.
1 to examine something or visit a place in order to learn about it: --
2 (of information) to seem to be true because it agrees with other information, or to discover whether information agrees with other information and is therefore likely to be true: --
The commissioner sent an investigator to check out the rumors.
Her statement checks out with most of the eyewitness reports.
3 to borrow a book or something else from a library (= a place with a collection of books, music, etc.): --