noun

• An image, symbol, picture, or other representation usually as an object of religious devotion.
• (religion, especially Eastern Christianity) A type of religious painting portraying a saint or scene from Scripture, often done on wooden panels.
• (by extension) A person or thing that is the best example of a certain profession or some doing.
• (graphical user interface) A small picture that represents something.
• (Internet, informal) An image used to represent a user; an avatar or profile picture.
• (linguistics, semiotics) A word, character, or sign whose form reflects and is determined by the referent; onomatopoeic words are necessarily all icons.
• Acronym of index currency option note, a type of financial instrument.