Record one's departure from a hotel by paying the bill, or from a conference or other function, as in As soon as my bags are packed I'll check out of the motel. [Early 1900s]
Leave hurriedly, make a quick exit, as in The minute I get paid I'm checking out. [Slang; 1920s]
Die, as in When he got cholera, he was sure he'd check out. [Slang; 1920s]
Withdraw an item after recording the withdrawal, as in I'll check out the tapes on your library card. [1930s]
Record, total the prices, and receive payment for a purchase, as in The cashier checked out and bagged my groceries in record time.
check something or someone out. Investigate or evaluate something or someone; observe carefully. For example, I don't know if you'll like the film; check it out yourself, or That man who's staring is probably just checking us out. [Slang; mid-1900s]
Pass close inspection, as in That rattle made me suspicious, but the repairman said the machine checked out completely.