Question: Is it possible to use material design themes for versions below Android 5.0?
According to [this link](https://developer.android.com/design/material/index.html), it is not the case:

> 
> Material design is a comprehensive guide for visual, motion, and
>  interaction design across platforms and devices. Android now includes
>  support for material design apps. To use material design in your
>  Android apps, follow the guidelines defined in the material design
>  specification and use the new components and functionality available
>  in Android 5.0 (API level 21) and above.
> 
> 
>

Answer: 
You can use the support library to have some of features in older versions as well as mentioned in below link:-

<https://developer.android.com/training/material/compatibility.html>

also as mentioned below you can visit this link as well:-

<http://android-developers.blogspot.in/2014/10/appcompat-v21-material-design-for-pre.html>
Yes it is possible to use material design themes below android 5.0. U can follow this link to see backward compatibility [link](https://developer.android.com/training/material/compatibility.html)

and to learn more about material design use this 
[link](https://developer.android.com/training/material/get-started.html)