The term "scale out" refers to a method used in computing and data storage, where additional resources are added to an existing system or infrastructure to increase its capacity. This is done by adding more servers, hard drives, or other components to handle increased demand for services or data processing. The goal of scaling out is to improve the overall performance and efficiency of the system without having to overhaul it entirely. It allows for a gradual expansion as needed, rather than requiring a complete replacement of existing hardware.