Narrow down refers to the act of reducing or refining options or choices to a more specific or manageable number. Some synonyms for the phrase narrow down are limit, restrict, narrow, specify, refine, focus, and zero in on. Other terms that can be used to describe the action of narrowing down are pinpointing, homing in, streamlining, whittling, winnowing, filtering, and curating. Using any of these synonyms helps to convey the idea of choosing selectively and making decisions more efficiently, which can be helpful in various contexts, including research, decision-making, and brainstorming.