Secrecy is the practice of keeping information hidden from others. When you maintain secrecy about a surprise birthday party, you're carefully guarding that information so the birthday person doesn't find out. When scientists work in secrecy on a new invention, they're protecting their ideas until they're ready to share them.

Secrecy involves actively concealing something, which makes it different from simple privacy. You might keep a diary private because your thoughts are personal, but you keep something secret when revealing it would spoil a surprise or cause problems. Governments use secrecy to protect national security information. Companies use secrecy to protect valuable business plans from competitors.

The word carries different feelings depending on the context. Sometimes secrecy protects something good, like when you plan a thoughtful gift in secrecy. Other times it feels sneaky or wrong, like when someone acts in secrecy to hide mistakes or bad behavior. A secret agent works in secrecy to gather intelligence. Scientists working on the atomic bomb during World War II operated under strict secrecy.

The phrase sworn to secrecy means promising not to reveal something. When your friend swears you to secrecy before telling you something important, they're trusting you to keep that information hidden.