I quoted the following and hope be satisfying the meaning of Big Data Testing
"Big Data Testing is a process that involves looking over and confirming the functionality of Big Data Applications. Big Data is the term for a collection of enormous amounts of data that traditional storage systems cannot handle.
There are several areas in it where its testing strategy is required. There are various types of testing in Big Data projects, such as Database testing, Infrastructure, Performance Testing, and Functional testing. It is defined as a large volume of data, structured or unstructured. Data may exist in any format, like flat files, images, videos, etc."