A symbol is a person, object, place, action, or image that stands for more than itself in a poem. It keeps its literal meaning while also suggesting an idea, feeling, or larger theme, such as a rose hinting at love or a storm suggesting turmoil. Unlike a metaphor, a symbol does not replace one thing with another; it adds an extra layer of meaning.
Example
A lantern shone on the empty pier,
its circle bright on the boards at night;
one small flame, and the poem let it mean
hope, and a hand held steady in the dark.
THE LONG HILL
Sara Teasdale
I must have passed the crest a while ago
And now I am going down--
Strange to have crossed the crest and not to know,
But the brambles were always catching the hem of my gown.
All the morning I thought how proud I should be
To stand there straight as a queen,
Wrapped in the wind and the sun with the world under me--
But the air was dull, there was little I could have seen.
It was nearly level along the beaten track
And the brambles caught in my gown--
But it's no use now to think of turning back,
The rest of the way will be only going down.
Related Definitions
[n] something visible that by association or convention represents something else that is invisible; "the eagle is a symbol of the United States"
[n] an arbitrary sign (written or printed) that has acquired a conventional significance