The noun metaphor is a word or phrase where the meaning of the object or idea is being replaced by another which is usually not literally applicable.
Synonyms are analogy, symbol, image or parable.
The word origins from Middle French (late 1500) methaphore and means “figure of speech by which a characteristic of one object is assigned to another, different but resembling it or analogous to it; comparison by transference of a descriptive word or phrase”. It also comes from Greek metapherein meaning “to transfer, carry over, change, alter, to use a word in a strange sense” (meta = over, across; pherein = to carry, bear).
In this speech the word sunshine was used as metaphor for joy.
The liberal party used metaphors as a way to explain a complex topic.
The professor used a tree as a metaphor for his students to grow into strong and wise adults.