There are several synonyms for the phrase "line of business" which refers to the specific industry or sector in which a company operates. Some alternative phrases that can be used include "field of work", "industry sector", "business area", "vertical market" and "niche market". Other phrases that can be used synonymously with "line of business" include "product line", "product category" and "business unit". The phrase "line of business" is commonly used in the world of finance and business, and is often included in corporate descriptions, job titles and industry reports. Alternative phrases are often used to add variety and nuance to writing, or to avoid repetition.