When we talk about miscible we are referring to the liquids property to mix in any proportion in a homogeneous phase, forming a solution. This term can be used to other phases as gases or solids too but it is commonly referred to liquids
When the mix of two liquids doesn't produce a uniform phase we can say that substances are immiscible and they are not able to form a homogeneous phase.
It most likely would be "miscible" because "soluble" refers to something being able to dissolve in water, "insoluble" is something not being able to dissolve or mix such as oil and water and immiscible is something not being able to mix without forming layers. Answer is: Miscible.
