This root comes from Latin and has to do with looking, seeing, and observing. While it might seem strange that the root for "speak" is connected to sight, it's related to the idea of conveying thoughts and ideas, which can be seen as a form of "showing" or "making visible."
Here are some other words with the "spec" root:
* Spectacle: a public display or performance
* Speculate: to think about something in a way that is not based on facts
* Inspect: to examine something carefully
* Prospect: a possibility for something good to happen in the future
* Specious: seeming to be true but actually false