What I see is one Greek word being discussed with so many English words. That is only a beginning. In fact as you read more widely and learn some the language, you will find a breadth of synonymity comparable to English.
If you knew more Greek words most of this discussion would be meaningless. There are Greek words similar to "credible", "admissible" and what ever other English words you are bringing up. Some of them have been discussed by various participants. In another place bringing up so many words involves some kudos. Here is shows you lack Greek words to do the same. There is no shame in that - everyone is encouraging you to learn more and improve.
As a beginner of course you couldn't be expected to know them, so they are not being introduced. You are being told the limits of the word you are trying to learn. When you reach an upper-intermediate compentency in Greek that will be both meaningful and managable for you. For now stick to your one-word definitions.