CMAT stands for the Common Management Admissions Test. It is a national-level MBA admission test , conducted by All India council for Technical Education (AICTE), a national-level Apex Advisory Body which is vested with the statutory authority for technical education in India. Since its introduction in 2011, a lot of (erstwhile) very popular state entrance exams have stopped conducting their own tests and instead use CMAT as the basis of the selection process. The list would include the likes of RMAT, UPCET etc.
There are 3500+ AICTE approved B-schools which are expected to take CMAT scores, translating to availability of over 4 lakh seats for a CMAT test-taker.