Metonymy is a figure of speech in which an item (either physical or abstract) is called not by its own name, but by the name of something closely associated with it. A metonym is a word or phrase used as a substitute for something that it is associated with.
> … and **the blood** of Jesus his Son cleanses us from every sin. (1 John 1:7b ULT)
> And he took **the cup** in the same way after supper, saying, “**This cup** is the new covenant in my blood, which is poured out for you.” (Luke 22:20 ULT)
The Bible uses metonymy very often. Speakers of some languages are not familiar with metonymy and they may not recognize it when they read it in the Bible. If they do not recognize the metonymy, they will not understand the passage or, worse yet, they will get a wrong understanding of the passage. Whenever a metonym is used, people need to be able to understand what it represents.
A throne represents the authority of a king. “Throne” is a metonym for “kingly authority,” “kingship,” or “reign.” This means that God would make him become a king who would follow King David.
> And he took the cup in the same way after the supper, saying, “**This cup** is the new covenant in my blood, which is poured out for you.” (Luke 22:20 ULT)
This verse also contains a second metonym: The cup, (representing the wine it contains) also represents the new covenant made with the blood Christ shed for us.