Which one is an abstract noun?

An Abstract Noun is usually the name of a quality, action, or state considered apart from the object to which it belongs.

Quality - Goodness, Kindness, Whiteness, darkness, hardness, brightness, honesty, wisdom, bravery
Action- Laughter, Theft, movement judgement, hatred
State - Childhood, Boyhood , Youth , Slavery, Sleep, Sickness, Death, Poverty

[source: High School English Grammar & Composition by Wren & Martin]