A prefix that means "equal," as in isometric, "having equal measurements."
A prefix used to indicate an isomer of an organic compound, especially a branched isomer of a compound that normally consists of a straight chain. The isomer is characterized by a Y-shaped branch at the end of the chain that consists of two "prongs". Each prong consists of one carbon atom. Thus isopentane contains five carbon atoms like normal pentane, but arranged as a chain of three carbons plus a Y-shaped branch of two carbons at the end.