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.
An allergy is an abnormal reaction by a person's immune system to a normally harmless substance. A person without allergies would have no reaction to this substance, but when a person who is allergic encounters the trigger, the body reacts by releasing chemicals which cause allergy symptoms.