A projecting bay window corbeled or cantilevered out from a wall(noun)
WordNet. Princeton University. 2010.
Use "oriel window" in a sentence
"She pointed to the many-paned oriel window projecting from the right-hand side of the house."
"The house was white, three stories with an oriel window on the top floor at the center, flowers in the window, like a set piece in marzipan."
"Crows shot from the eaves, and an oriel window seemed to have collapsed, leaving a gaping maw, but smoke was issuing from a chimney, so someone was in residence."