Encryption
Etymology
From Greek "kryptos," hidden — the same root as crypt and cryptic — via the sense of writing something in cipher. The prefix "en-" makes it an action: to put into a hidden form. Modern usage distinguishes it sharply from mere encoding, because encryption depends on a secret key, not just a rearrangement anyone can reverse.
noun · /en-KRIP-shun/
Scrambling information with a key so that only someone holding the matching key can read it.
What it names
The invisible lock behind private messaging, online banking, and the padlock in your browser — the reason a stranger on the same Wi-Fi can’t read your texts.
Example
End-to-end encryption means even the messaging company itself can’t read what you send.
Related idea
Encryption is stronger than a password: a password gates access to a system, but encryption transforms the data itself, so stolen files stay unreadable without the key.