How can you define intelligent system?

Which, use knowledge to understand even your expressions along with your thinking also

These are the systems which analyze large amounts of data to deduce relationsships between some entities. 

Good day my friend!

I am kinda confused of your question. But I will try to answer. I hope this is helpful.

↔Any formal or informal system to manage data gathering, to obtain and process the data, to interpret the data, and to provide reasoned judgments to decision makers as a basis for action. The term is not limited to intelligence organizations or services but includes any system, in all its parts, that accomplishes the listed tasks.

Thanks!