As google does not provide any API for google Dictionary. This Self Project intends to create one.
To use just pass the query string with parameter define equal to the word you want definition of.
Eg. /?define=hello, will give you definition of hello as provided by Google in JSON format.
You can see existing and add new feature proposals on the projects GitHub page. Pull requests are welcome!
If you need any assistance or find any bugs, feel free to contact me directly via email or create a new issue on the GitHub page.