Is it ensure, insure, or assure?
1610s, from Italian balcone, from balco "scaffold," from a Germanic source (perhaps Langobardic *balko- "beam," cf. Old English balca "beam, ridge;" see balk) + Italian augmentative suffix -one. Till c.1825, regularly accented on the second syllable.
external extension of an upper floor of a building, enclosed up to a height of about three feet (one metre) by a solid or pierced screen, by balusters (see also balustrade), or by railings. In the medieval and Renaissance periods, balconies were supported by corbels made out of successive courses of stonework, or by large wooden or stone brackets. Since the 19th century, supports of cast iron, reinforced concrete, and other materials have become common.