nonsense
Emphasis
Alienate
Yuletide
Tutelage
enormous
A noun for garbage meaning "nonsense" could be claptrap or malarkey. The only other common synonym for trash or rubbish that has 8 letters would be foulness.
A synonym for "grateful" that has eight letters is "thankful."
Assembly/assemble
forebode, forecast, foretell
deserted?
doubtful, unsavory, slippery
ten years