To concrete; to curdle; to congeal; to change from a fluid into a fixed substance, or solid mass; as, to coagulate blood; rennet coagulates milk. This word is generally applied to the change of fluids into substances like curd or butter, of a moderate consistence, but not hard or impenetrable.

To curdle or congeal; to turn from a fluid into a consistent state, or fixed substance; to thicken.