Securities and Exchange Board of India (Merchant Bankers) Rules, 1992 ― A merchant banker has been defined as any person who is engaged in the business of issue management either by making arrangements regarding selling, buying or subscribing to securities or acting as manager, consultant, adviser or rendering corporate advisory services in relation to such issue management.
Random House Dictionary―Merchant banker is an organization that underwrites securities for corporations, advices such clients on mergers and is involved in the ownership of commercial ventures. These organizations are sometime banks which are not merchants and sometimes merchants who are not banks and sometimes houses which are neither merchants nor banks.