What does the "s" mean in s-cis and s-trans conformations

I am learning about conjugated unsaturated systems, and came upon s-cis and s-trans conformations in conjugated dienes. 


So what does the "s" mean in s-cis and s-trans conformations? 




The s stands for single, as in single bond. It means the double bonds are cis or trans to each other based around the single bond.
[![enter image description here](https://i.stack.imgur.com/1X6kA.png)](https://i.stack.imgur.com/1X6kA.png)


It is a common enough expression to search for, if more information is required.


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