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.
When the interaction causes an increase in the effects of one or both of the drugs the interaction is called a synergistic effect. An additive synergy occurs when the final effect is equal to the sum of the effects of the two drugs (Although some authors argue that this is not true synergy).