Something in the world of the senses, including an action, that reveals or is a sign for something else, often abstract or otherworldly. A rose, for example, has long been considered a symbol of love and affection.
Every word denotes, refers to, or labels something in the world, but a symbol (to which a word, of course, may point) has a concreteness not shared by language, and can point to something that transcends ordinary experience. Poets such as William Blake and W.B. Yeats often use symbols when they believe in—or seek—a transcendental (religious or spiritual) reality.
A metaphor compares two or more things that are no more and no less real than anything else in the world. For a metaphor to be symbolic, one of its pair of elements must reveal something else transcendental. In “To the Rose upon the Rood of Time,” for instance, Yeats’s image of the rose on the cross symbolizes the joining of flesh and spirit. As Cleanth Brooks and Robert Penn Warren write in their book Understanding Poetry (3rd ed., 1960),“The symbol may be regarded as a metaphor from which the first term has been omitted.”
See also allegory and imagism.