ogee or ogive arch: An arch with a pointed apex, formed by the intersection of two S curves usually confined to decoration and not used in arcade arches. Ogee arches were used only in the late Gothic period.
Other types of arches:depressed, horseshoe
orant (orans) figure: A standing figure with both arms raised. This was a gesture of p-rayer in the Early Christian period.
oriel: A projection from the upper story of a building. Oriels very often contain windows.