Decabromodiphenyl ether (also known as decaBDE, deca-BDE, DBDE, deca, decabromodiphenyl oxide, DBDPO, or bis(pentabromophenyl) ether) is a brominated flame retardant which belongs to the group of polybrominated diphenyl ethers (PBDEs).
Commercial decaBDE is a technical mixture of different PBDE congener

Congener

Congener has several different meanings depending on the field in which it is used. Colloquially, it is used to mean a person or thing like another, in character or action.-Biology:In biology, congeners are organisms within the same genus...

s, with PBDE congener number 209 (decabromodiphenyl ether) and nonabromodiphenyl ether being the most common.