In-house refers to activities or functions that are performed within a company or organization, rather than being outsourced to an external provider. There are several synonyms for in-house that can be used interchangeably, depending on the context and specific meaning intended. Some of these include internal, on-site, in-company, proprietary, and captive. These terms all emphasize the concept of being located within an organization or company, and highlight the idea of the organization having control over the activity or function in question. Using synonyms for in-house can add variety and depth to your language, and help you communicate more effectively with others in various business contexts.