There are two basic words in Scripture for covenant.
Brit or brith - the Hebrew word, used in the Old Testament
Diatheke - the Greek word used in the New Testament
This Hebrew word occurs in the name of the well-known Jewish organization, Bnai Brith, which means, literally, "Sons of Covenant." Each of these words - diatheke in Greek and brith in Hebrew is regularly translated by two different English words: covenant and testament.
The English word used in each case varies according to the context. In our language, we do not usually think of covenant and testament as being the same. We limit the word testament to a legal document which, as Scripture points out, comes into force only after the death of the one who made the testament.
"For where there is a testament, there must also of necessity be the death of the testator. For a testament is in force after men are dead, since it has no power at all while the testator lives." Hebrews 9:16-17
However, on the other hand, we do not associate covenant with the death of the parties to the covenant. Yet, in the concepts of Scripture, this distinction between testament and covenant is not valid.
What is God saying to us? What is His meaning of the word covenant? It is not possible to speak for God. However, it is suggested that the root meaning of the Hebrew word brit is "to bind,". Even though some scholars differ on the meaning of this word, it is certain that a covenant is binding. The root meaning of the Greek word diatheke is "to set something out in order." This meaning leads us to see that God is setting forth specific terms and conditions.