The phrase "same dictionary" means that two or more people are using the same language and definitions to understand and communicate with each other. It suggests that they share a common understanding of words and their meanings. Full definition
I don't think he / she uses the same dictionary most rational people do. (religion.blogs.cnn.com)
The first few weeks those words may not even seem like they should be in the same dictionary, but as you settle into your new role with your new baby you can take some steps to rediscovering the sexy that still lurks within. (thebabycorner.com)