Someone in charge of a client's account for an advertising agency or brokerage or other service business WordNet 3.0 & Open English WordNet

Account executive is a role in sales, advertising, marketing, and finance involving intimate understanding of a client company's objectives and products and a professional capability to provide effective advice toward creation of successful promotional activities and strategies. Wikipedia

A job title given by a number of marketing agencies Wikipedia Disambiguation

In business management Wikidata

An executive in an advertising agency, or public relations firm who manages a client's account. Wiktionary