Greek word "Metonomy" means "a change of name". In metonomy the name of one thing is substituted for that of another with which it is closely associated. The association of one thing with another is so deep that whenever we think of one thing we can remember, the other which is substituted by former. For example-
"The crown is used to mean monarchy or when we think of the 'pen' we think of the writer. Thus 'Fear not' we are loyal to the throne".
In these sentences the throne is not physically a part of the king, the idea of kingship is closely associated and throne is used as the substituted of the king. So it is the metonomy.
