Originally Posted by gfunkdave

No, it means the connection is encrypted and the browser has validated that the certificate presented by the web server belongs to that server. Those two conditions (encryption and verification against Man In the Middle attacks) are what SSL/TLS are designed for. Any browser will throw errors if a website you visit presents a certificate that doesn't match the site it's connected to. In those cases, the padlock won't appear and the browser will tell you there's something wrong with the site's security.

Here's an example: https://wrong.host.badssl.com/