I was thinking yesterday about some basic insights into words. It's all stuff I've said before, but they're worth repeating.
1. The same word will normally be translated by several different words into another language.
So you can do a "concept" study by looking at all the places an English word is used in a particular version of the Bible. It is not a bad thing.
But you should keep in mind that you will not be studying the same underlying word. You're trusting the English translators of whatever version to have used the right translation word. Also see #3 below.
2. The same underlying Greek or Hebrew word will normally be translated in English by more than one word. Words have a range of meanings. They do not always mean the same thing. They do not always play out some core meaning. They are not in any way limited by what they used to mean or what the different parts of the word break apart to seem to mean.
So ekklesia did not mean the "called out ones." To sin is not about missing the mark as in missing an archery target. Baptism isn't always about immersion. That's just ghetto.
3. When I was in college, I was enamored of Kittle and theological dictionaries. And weren't these put together by giants of biblical interpretation? So what is the theological significance of a Greek word? Then what was the magic theology in the Hebrew word that corresponded to the Greek word?
But this is all premodern. It unreflectively thinks that there is this singular meaning to which all the words point. Meaning doesn't work like that. The contextual meaning of a word at any point of the Bible is in how it was used at the point when that word was used. There is no common, timeless meaning to which all the words point. That's the task of theology and just isn't the way the biblical words were used.
So there's no point in looking up the Hebrew word for righteousness when you are studying Paul's use of the word righteousness--that is, unless you have reason to believe that he knew and was "using" that meaning. The meaning of righteousness in Hebrew is only as relevant to the interpretation of Paul as he used that meaning. In a case like the book of Hebrews, whose author does not seem to use the Hebrew OT, the Hebrew meaning of some original text he quotes is completely irrelevant to the meaning of Hebrews.
The original meaning of the Hebrew OT is only relevant to the interpretation of the NT to the extent that the NT authors knew and used it.
Can God have had other meanings to the OT in mind? Sure, but don't confuse that with what the words meant in context, in what their first authors and audiences understood the words to mean.