Opinion leader refers to a person within a reference group who, because of special skills, knowledge, personality, or other characteristics, exert social influence on others.
Some experts call this group the influential or leading adopters. When these influential talk, consumers listen. Marketers try to identify opinion leaders for their products and direct marketing efforts to ward them.
Definition 2.
Opinion leader is the person who offers informal advice or information about a specific product or product category, such as which of several brands is best or how a particular product may be used. Opinion leaders are often highly confident, socially active, and frequent users of the category.