n (uncountable|aeronautics) Any varnish used to coat a part, such as an airplane wing or a hot-air balloon in order to waterproof, strengthen, etc.
n (uncountable|slang) Any narcotic or similar drug which produces euphoria or satisfies an addiction; particularly heroin, although amphetamine, methamphetamine,
v (transitive|electronics) To add a dopant such as arsenic to (a pure semiconductor such as silicon).