Multicoat is an adjective that describes something that has several layers of a substance, such as paint, polymer, or waterproofing membrane. It can also be a verb that means to apply multiple coats of a substance on something.

Some examples of multicoat are:
A multicoat paint system that provides better protection, durability, and  appearance than a single coat.
A multicoat polymer blend that has improved properties, such as strength, stability, and compatibility.
A multicoat waterproofing membrane that prevents leakage, corrosion, and damage to the surface.