When you are studying a word, it’s often a good idea to look at synonyms and antonyms for that word as well. For example, if you were studying the English word run, you might also want to consider how words like sprint, jog, or even gallop overlap in meaning with run, and to what extent they are different. You may also want to consider how run and its synonyms are transformed into other parts of speech: What can the word jogger tell us about the meaning of run that runny cannot?
Finding words that are related to one another in meaning is also useful for studying the Bible, or else resources like Girdlestone’s Synonyms of the Old Testament or Trench’s Synonyms of the New Testament wouldn’t exist — not to mention Louw and Nida’s Greek-English Lexicon of the New Testament based on Semantic Domains. The Louw-Nida dictionary is particularly interesting, since it arranges all the words of the Greek New Testament by means of a hierarchical taxonomy, where each entry rests within a “domain” of meaning alongside any other words that have some degree of semantic overlap.
That’s all fine and good if you’re only studying the Greek of the New Testament. But what about the Old Testament?