means A symbol, image, or person regarded as a representative emblem of something—or, in computing, a tiny clickable picture that stands for a program or file.

from From Greek 'eikon,' meaning likeness or image, which passed through Late Latin 'icon.' For centuries it named the sacred painted images of Orthodox Christianity—Christ, the saints, the Virgin—venerated on wooden panels. The religious sense bled outward into 'anything held up as a revered representation,' and in the 20th century computing borrowed it once more for the little pictures on a screen.