One of my favorite word study tools when doing in depth Bible study has always been Vine’s Complete Expository Dictionary written by W.E. Vine and first published in 1940. It was the second Bible study book I bought over 20 years ago, Strong’s Exhaustive Concordance being the first. Those 2 books were great investments; I definitely got my money’s worth out of them.
However, I recently found Vine’s Expository Dictionary of New Testament Words at www.studylight.org. Instead of thumbing through the pages of a book, you can do a Greek word study with the click of a mouse. The best part? It’s free! Click here to access it.