Symbol: something that stands for or suggests something else by reason of relationship, association, convention, or accidental resemblance; especially : a visible sign of something invisible. <the lion is a symbol of courage> More examples?
What is Symbolism? If there is one central tenet held by Symbolist artists, it is that life is fundamentally mysterious, and the artist must respect and preserve this mystery. Thus they insisted on suggestion rather than explicitness, symbols or equivalents rather than description, in both painting and poetry. Choosing music as their model, Symbolists found the creation of a mood to be as important as the transmission of information, and sought to engage the entire mind and personality of the viewer by appealing to the viewer’s emotions and unconscious mind as well as intellect.