Is dirt an abstract or concrete and why?
"dirt" is a concrete noun because you can see it and touch it ...
"freedom" is an abstract noun because it's not visible or touchable ...
http://www.chompchomp.com/terms/concretenoun.htm
http://www.chompchomp.com/terms/abstractnoun.htm
Dirt is considered a concrete noun. Concrete nouns are things that can be perceived by our five senses: sight, hearing, taste, touch, and smell. Dirt can be seen, felt, and even smelled, which makes it a concrete noun. It can be further classified as an uncountable noun, as it typically refers to a mass or quantity rather than individual units.
If you want to dig up the dirt on someone, then it becomes just information, a more abstract quantity.
Many nouns in English have several meanings, some concrete, others more abstract, or metaphorical.