Narcissism is the pursuit of gratification from vanity or egotistic admiration of one's own attributes. The term originated from Greek mythology, where the young Narcissus fell in love with his own image reflected in a pool of water.
In general, synergy (pronounced SIN-ur-jee, from Greek sunergia, meaning cooperation, and also sunergos, meaning working together) is the combined working together of two or more parts of a system so that the combined effect is greater than the sum of the efforts of the parts.
Synergy may also refer to the cost reduction a merger brings about by eliminating or streamlining redundant processes. Synergy usually has a positive connotation, but one also occasionally hears of negative synergy, such as when the management teams of newly merged corporations do not work well with each other.