Question

Which of these books would not be useful if you wanted a synonym for the word aggravate?

1) Roget's Thesaurus
2) O.E.D.
3) a common dictionary
4) American Dialect Dictionary

Answer 1

The book that would not be useful if you wanted to find a synonym for the word aggravate is 4) American Dialect Dictionary, because that dictionary would just explain some less known words used in different parts of America.
The other dictionaries do provide synonyms.