The phrase "pin down" is commonly used to describe the act of identifying or clarifying something. However, there are many synonyms for this phrase that can be used to convey the same meaning. Some possible alternatives include: nail down, define, specify, determine, delineate, articulate, establish, pinpoint, clarify, and confirm. Each of these words conveys a slightly different nuance, and choosing the right one will depend on the specific context and level of precision required. Regardless of which synonym is used, the goal remains the same: to bring clarity and understanding to a particular topic or issue.