I think it is helpful to regularly look up the definitions of some of the common words we use on a daily basis, especially words relating to our faith. Many times we grow up hearing familiar words without ever examining what they really mean. Even if we feel we have a handle on the particular word, it is always nice to have a refresher. I recently made note of these:
Repent is from a Greek word used to describe a change of mind that results in a change of behavior.
-John MacArthur, Because the Time is Near
Believe literally means: to be; to exist; to live or have your being live in accordance with.
-Paris Reidhead, Getting Evangelicals Saved