My copy of the Oxford Greek-English Learner’s Dictionary by D N Stavropoulos is hands down one of the most used and most useful resources that I own!
In fact, I’ve used this dictionary so often that I had to repair the spine and all of the corners with packing tape.

Why do I like this resource so much? Its almost 1,000 pages of definitions capture subtleties of word meanings that make translating a word a rich and nuanced process.
Let’s take a look at the word <<πέφτω>> as an example.
While the word <<πέφτω>> could simply be translated as “fall”, the Oxford Greek-English Learner’s Dictionary provides 14 categories of definition spanning three columns of text. Example sentences and idiomatic usages are provided, such as <<πέφτω από τα σύννεφα>> meaning “come down to earth with a bump” or “be flabbergasted” (p 699) and <<πέφτω με το κεφάλι>> meaning “to fall headlong” (p 699).
This variety of definitions and examples means that if you are translating a word from a context, you can choose the meaning that captures the essence of that particular context.
This dictionary has become an essential resource in my Greek learning experience. Perhaps you too would find it to be an important tool in your learning toolkit.
Do you have a favorite resource for learning Greek?