to think of, to think up, to devise, to invent, to formulate, to create, to dream up, to generate, to produce, to develop, to work out, to conceive, to contrive
concept - notion - thought - plan - scheme - design - intention - inspiration - brainchild - insight - vision - impression - suggestion - proposal - conception - belief - view - approach - perception - inkling - hunch
An idea is a mental concept or thought formed in the mind, often as a response to a question, problem, or observation. Ideas can be abstract or concrete, simple or complex, and may arise from experience, imagination, or logical reasoning. They form the basis of understanding, innovation, and decision-making in many areas of life, such as science, art, business, and everyday problem-solving. An idea can be the starting point for plans, projects, theories, or inventions, and is often refined through discussion, reflection, and experimentation.