An abstract noun is
usually the name of a quality, action or state considered apart from the object
to which it belongs. Abstract nouns are not physical entities and hence cannot
be touched; that is why they are called abstract nouns. Some abstract nouns,
however, can be observed by one of the other senses.
For
example: fitness, honesty, laughter,
hatred, childhood.
Concrete nouns refer to
physical entities that can usually be touched.
For
example: chair, atom, stone, tool.