A French door[24] has two rows of upright rectangular glass panes (lights) extending its comprehensive length; and two of those doorways on an exterior wall and without a mullion separating them, that open up outward with opposing hinges to a terrace or porch, are called a French window. Sensible Vocabulary: https://repostyou.com/comprehensive-guide-to-cleaning-equipment-window-cleaning-pressure-washing-water-fed-pole-systems-soft-washing-and-solar-panel-cleaning/