icòna sf [from Russian ikona, and this from Gr. biz. εἰκόνα, gr. class. εἰκών -όνος «image»]. 
1. Sacred image (representing Christ, the Virgin, one or more saints) painted on a wooden tablet or metal plate, often decorated with gold, silver and precious stones, typical of Byzantine art and, later, of Russian and Balkan art.
2. lit. Sacred image in general, painted or sculpted; in this sense the form icòne is also used (taken directly from classical Greek, as are the various compounds with icono-).
3. In semiology, according to the terminology of Ch. S. Peirce (1839-1914), one of the three fundamental types of signs (the other two are the index and the symbol), distinguished according to the relationship that unites them to external reality: it is the sign that is in a relationship of similarity with this, in that it presents at least one of the qualities or has the same configuration as the signified object (for example, a bloodstain for the color red, or an onomatopoeia, a diagram, the plan of a building, and the like).
4. In computer science, in operating systems with a graphical interface, a small image that symbolically represents a command, a function or even a document or an operating program, which appears on the screen of a computer (often with the characteristics of a button) and which, when selected by the user using a specific tool (such as a mouse or a light pen), starts the function or program it symbolizes (for example, the figure of a wastepaper basket for the command "delete the document"): click on the program icon; drag the icon from one folder to another.
5. An emblematic figure or character of an era, a genre, an environment: Marylin Monroe is the icon of femininity.