A substance, device, or agent that causes coagulation; something that makes liquids thicken or clot.
From coagulate plus -or suffix (one who does or that which does). Latin -or endings typically denote an agent or doer of the action.
Aluminum sulfate, a common coagulator in water treatment plants, removes impurities by making them clump together—it's how your drinking water gets cleaned on a massive scale.
Complete word intelligence in one call. Free tier — 50 lookups/day.