It's a marketing buzzword from some US defense company. It stands for "multi-role electronically scanned array", but what it actually means is mediocre electronically scanned array. It's not an engineering term with actual meaning like PESA or AESA.
It's the name of the radar itself.
In the same way that "EOTS" and "EODAS" are the names of the specific subsystems on the F-35, and do not refer to the entire class or type of sensors.