The term "well-rounded" refers to someone or something that is fully developed and has multiple facets or abilities. A well-rounded person has skills, knowledge, and interests in various areas, making them versatile and adaptable. This can apply to both individuals and things, such as education or experiences that encompass a broad range of subjects.
The phrase "well-rounded" comes from the combination of the word "well," meaning in a good or satisfactory manner, and "rounded," which derives from "round," referring to something that is shaped smoothly or completely. The idea is that a person is 'rounded' in the sense of having developed multiple aspects of their personality or skill set.