Answer is in the "Root".
Understand the root of an Arabic word to get to the basics of where and how a word comes about.
In Arabic, one root gives birth to many words.
Remember:- No matter how many words come out of a root, the meaning and concept of the words should carry the essence of their root. If this is not the case, then you have lost the meaning of the word, thus resulting in loss of message.
Here is an example:
You have been told the meaning of "Raheem" to be Merciful, or the one who forgives.