What is synecdeche?

Synecdoche is a figure of speech in rhetoric, in which a part of something is used to refer to the whole, or the whole is used to refer to a part. Synecdoche can also be used to suggest a part-whole relationship between two words or phrases.

It is a form of metonymy, in which a thing or concept is referred to by the name of one of its parts.

* For example:

"All hands on deck!" (refers to the entire crew of a ship, not just their hands)

"The pen is mightier than the sword." (refers to the power of writing and ideas, not just the literal pen)

"Give us this day our daily bread." (refers to all of our daily needs, not just bread)