闪开 is a resultative verb compound (RV) meaning to dodge or avoid something by moving quickly to the side. The second character 开 (kāi) acts as a result complement indicating the outcome of moving away or opening space. You'll often hear it in urgent commands like 闪开! (Get out of the way!) or in narrative descriptions of dodging an obstacle. It's more specific than the general 躲避 — it always involves physical or figurative sideways movement to escape a direct hit or collision.