Some figures of speech (for example, anaphora or anthropomorphism) are very popular. Every poet uses them.
Synecdoche isn't a widespread literary device.
What is Synecdoche?
Let's begin with an example from everyday life:
She decided to buy a new set of wheels.
What about this sentence? A woman is going to buy a car.
In synecdoche a part of something represents the whole. It is also possible, that a whole represents a part:
Italy has won four World Cups - in 1934, 1938, 1982, 2006.
We said “Italy” instead of “Italy's national soccer team”.
Examples in English Literature
The Eyes around - had wrung them dry -
And Breaths were gathering...
I heard a Fly buzz when I died by Emily Dickinson
Tell that its sculptor well those passions read
Which yet survive, stamped on these lifeless things,
The hand that mocked them, and the heart that fed;
And on the pedestal, these words appear:
My name is Ozymandias, King of Kings;
Look on my Works, ye Mighty, and despair!
Ozymandias by Percy Bysshe Shelley
And let us mind, faint heart ne'er wan
A lady fair:
Wha does the utmost that he can,
Will whiles do mair.
To Dr. Blacklock by Robert Burns
The figure forms a picture, helps readers to understand the author's thoughts, as you see.
Metonymy and Synecdoche
Synecdoche are often called metonymy by mistake. They both use a word or a phrase to represent something else.
Nevertheless in metonymy the phrase or the word we use to describe another thing doesn't always denote a part of that thing.
Speaking about a businessman, we can call the person “suit”. It is a case of metonymy. Two objects are closely linked, but suits aren't necessarily businessmen's part.