what is mind

To understand mind you should understand it by yourself by your own experience , as experienced by me mind is nothing but accumulation of thoughts based on memory and if we go in depth as per spirituality 

Mind = content of consciousness ( memory + past experience + knowledge )

Mind is different in every living entity as human mind is evolved therefore everyone is suffering there memory and the expectation of future accomplishment 

the cosmic mind also has a material process of remembering things also where sanskars or conditioning are feaded as we say our hardware is brain or boday and soaftware or the running programme is the conditioning on the basis of that we act and live