Usually defined as earnings plus depreciation of intangibles.
More generally, you start with earnings, add depreciation and possibly other expenses back in, and possibly subtract some sources of income out, to arrive at a number that you think gives a better indication of a company's profitability than earnings does.
One example: if the company has acquired another, it is probably depreciating goodwill, making earnings artificially low.
The relevant numbers for analyzing cash flow are available in the cash flow statement.
Sometimes cash flow is defined as omitting all depreciation; this definition would overlook the real expense of any asset gradually getting "used up", and requiring eventual replacement.
The "meaningful" cash flow quantity is free cash flow.