When an idea is solidified or takes on a tangible form, it becomes concrete. However, there are many other ways to express this concept using synonyms. For example, the idea could take shape or be realized, giving it a physical presence. It could also be manifested or actualized, indicating that it has transformed from imagination into reality. Alternatively, the idea may become substantial or take on substance as it gains more concrete details. Other synonyms could include materialize, coalesce, or concretize. No matter which word is used, it is clear that the idea has moved beyond mere abstraction to become a concrete, actionable concept.