When you decide to study a New Testament word, the normal procedure is to stick to a single Greek word.  Even if another word looks similar, the meaning might be different.

In English, for instance, compliment is not the same as complement, even though many people can't tell them apart.  The first means "to say something nice about you"; the second means "to make something complete."

There are times, however, when you will want to look at two or more words that happen to belong to the same "family" of words.

Why would you want to bother comparing other words?  I usually adopt this tactic when I'm studying a word that only appears two or three times in the New Testament.  You can't get a sense of the word's use with only two samples; you need a larger selection so you can find patterns!  Exploring related words can broaden your search and give you more material to help you bild a picture of the word's usage.

Here are two samples that show how a broader search can deepen your understanding of a word:

homologeo = confess

We have traced this word elsewhere and found that it usually means "to acknowledge a person or proposition."  The best-known use of the word appears in 1 John 1:9:  "If we confess our sins . . ."  It is a little surprising to find that this is the only verse in the New Testament that uses the word in regard to sin.

There is another word, however, that is closely related to homologeo.  The word appears 10 times in the New Testament, and four of those verses use the word to describe confession of sins (Matthew 3:6; Mark 1:5; Acts 19:18; James 5:16).  You might think of exomologeo as an intensified form of homologeo.  In any case, you can add detail to your understanding of both words by comparing the two.

If you want to study the other references using exomologeo, you can use this list:  Matthew 11:25; Luke 10:21; 22:6; Romans 14:11; 15:9; Philippians 2:11.

sophron = sober, sensible, temperate

According to 1 Timothy 3:2, an elder in a Christian church should be sophron . . . whatever that is.  When I look at the other references where the word appears, here's what I find:

Titus 1:8 -- Elders or overseers shouldbe sophron.

Titus 2:2 -- Older men should be sophron.

Titus 2:5 -- Older women should encourage younger women to be sophron.

This looks like a dead end.  All I know is that sophron is a good thing that Christians should have.  How do I find out more?

Look at a Greek lexicon.  Find the word sophron, then use your peripheral vision.  Look an inch or two up and down the page, and you will find several other words that look remarkably similar:

sophroneo - a verb that appears in Mark 5:15; Luke 8:35; Romans 12:3; 2 Corinthians 5:13; Titus 2:6; and 1 Peter 4:7

sophronizo - a verb that appears in Titus 2:4

sophronismos - a noun that appears in 2 Timothy 1:7

sophronos - an adverb that appears in Titus 2:12

sophrosune - a noun that appears in Acts 26:25 and 1 Timothy 2:9, 15

Twelve more verses to check!  And when you do, you will find something that will give you a much more tangible picture of the word meaning.

Mark 5:15 and Luke 8:35 both use one word from this group to describe the demon-possessed man who lived in the cemetery and was totally out of control.  Once Jesus cast out the demons who were tormenting the man, people found him "clothed and in his right mind."  Perhaps we can think of sophroneo as the opposite of insanity.

Acts 26 reinforces this concept.  Paul has been presenting his defense to Festus the Roman governor, who exclaims, "Paul, you are out of your mind!  Your great learning is driving you mad."  In response, Paul asserts, "I am not out of my mind, most excellent Festus, but I utter words of truth and sophrosune" (verses 24-25).   Once again, the sophron word group carries the idea of something that is a contrast to insanity.

There are more insight contained in the other references, but even this one idea is worth the effort of scrutinizing a word family.

A little caution is in order when we study related or "cognate" words.  There can be subtle shifts in meaning as we pass from one to the other.  However, a careful comparison of the "cousins" to your word can yield fascinating insights.