Doc is a casual, friendly way to say “doctor.” You might call your family doctor “Doc” if you know them well, or you might hear someone in an old Western movie say “Thanks, Doc!” to the town physician. The word feels warm and personal, like you're talking to someone you trust.

In hospitals and medical offices, patients sometimes use “Doc” as a nickname for their doctors, though it's more informal than saying “Dr. Smith” or “Doctor Smith.” The word suggests familiarity and respect without being stiff or formal.

Doc can also be short for “document,” especially in computing. When you save a file on your computer, you might see it end in “.doc” or “.docx,” which tells you it's a document file, usually something you can open with word processing software. You might hear someone say “Send me that doc” when they want you to email them a file.

The word appears in nicknames too: someone named Doc might not be a doctor at all, just someone who got the nickname as a kid and it stuck. The name has a friendly, trustworthy feel to it, which is probably why it's lasted as a nickname for well over a century.