Coherent refers to something that is clear, logical, and connected in a way that makes sense. It is used to describe a set of ideas, thoughts, or actions that are related to each other and follow a consistent pattern or structure. A coherent argument or speech is one that is well-organized and easy to follow, with each point logically leading to the next. Similarly, a coherent piece of writing or art is one that is clear, concise, and effectively conveys the intended message or emotion. In physics, coherence refers to the property of light waves that are all in step with each other, producing a smooth and steady beam.