Symbol
A form that stands for a concept by learned convention alone, without resembling it.
In practice
A symbol represents something by agreement alone; nothing in its shape resembles what it means. A heart for love, a dove for peace and a green cross for a pharmacy all have to be learned. Because the agreement is cultural, a symbol that is clear in one country can be meaningless, or mean something else, in another, so products sold internationally test their symbols with local audiences.
Often confused with Icon
A symbol works by learned convention; an icon works by resemblance, looking like what it represents.
Try this
Find five symbols around you and note whether a visitor from another country would understand each one.