Concrete Noun:
* When referring to a physical object, like a book containing words and definitions:
* "I bought a new dictionary at the bookstore."
* "The dictionary was heavy and full of interesting words."
Abstract Noun:
* When referring to the concept of a collection of words and definitions, regardless of its physical form:
* "The dictionary is a valuable tool for learning new words."
* "We need to update the dictionary with new words and definitions."
In these cases, the dictionary is not a specific physical book, but rather the general idea of a collection of words and their meanings.
Therefore, the context determines whether "dictionary" is a concrete or abstract noun.