1. it is by far the best dictionary.
2. It is far and away the best dictionary.
3. it is far the best dictionary.
4. it is a lot the best dictionary
(Which ones are correct? Do you have more expressions which can be used before the superlative degree?)
1 and 2 are correct. You can also say - It is the verb best dictionary. However, when using the superlative, it is not necessary to use other words. You can't get any better than best.
"very" instead of "verb" -- right?