Synecdoche (the E is pronounced like in recipe) is a literary device in which a part of something is used to refer to the whole (or vice versa). It’s mainly considered a poetic device, and most examples that people provide are from poems. In this passage from Samuel Taylor Coleridge’s “The Rime of the Ancient Mariner,” for example, the word wave stands in for the sea:
The western wave was all a-flame.
The day was well was nigh done!
Almost upon the western wave
Rested the broad bright Sun
We use the word wave similarly when we use the phrase on the wave. Similarly, we can say a bird is on the wing when it’s flying. These are the two examples I was given when I was introduced to the term, back in, I believe, my final year of primary school. I was intrigued by this strange-sounding and -looking word, and wanted to think of other examples, though nothing really came to mind. I soon came to think of it as a purely literary device that was interesting, but not hugely relevant to my life. But now wiser and with a wider vocabulary, I can see that synecdoche is actually fairly common.