Something that stands for something else; an emblem; a type.
A character, mark, etc., indicating something, as a quantity in mathematics.
It is not some superstition or some symbol. – The Ball and The Cross by G.K. Chesterton
How clearly it had stood out in the darkness, how brightly the rays of the sun had declared the symbol of Aton! – There was a King in Egypt by Norma Lorimer