an image, subject or style that is traditionally or popularly used
to represent, symbolize or associate meaning to another thing;
a visual image used to represent a religious figure;
symbolism associated with an image
Here is an example of contemporary iconography -
New York's I Love New York image.
The heart icon has long been associated with "love".
It's symbolism is recognized by most people and now needs no explanation to the meaning. An Icons beginning can be intentional or accidentally but it's the repetition that gives its meaning strength.