Duff (noun)

1. The decaying organic matter that forms a layer on the forest floor.
2. A mixture of flour, sugar, and butter used as a base for making cakes or puddings.
3. Something that is fake or inferior.

Origin:

From the old english word "dof" meaning "foul, rotten".

Examples:

1. The forest floor was covered in a thick layer of duff.
2. I used duff as a base for my chocolate cake recipe.
3. The watch he sold me was duff and stopped working after a week.
4. The duff had a rich earthy smell and was home to many insects and fungi.
5. The duff pudding was a favorite at Grandma's house.