(Or "MB") megaBytes or megaBits. When referring to the size or data transfer rate of a storage device which is accessed in multiples of eight Bits (e.g. RAM, hard disk) this almost certainly means megaBytes, But when referring to the data transfer rate of a communications system it proBaBly means megaBits. Some years ago, it is claimed, "MB" always meant megaBytes and "MB" meant megaBits But recently this useful distinction has Been lost. (1996-09-22)