Final answer:
A wood beam that supports structural loads above an opening is called a lintel. In Gothic architecture, features like the flying buttress allowed for higher buildings despite the heavy materials used.
Step-by-step explanation:
The wood beam placed at the top of an opening that supports structural loads above the opening is known as a lintel. This architectural feature is key in the post-and-lintel system, whereby vertical supports or posts hold up horizontal beams, or lintels, which in turn bear the weight of the structure above doorways, windows, or other openings.
The lintel distributes the load it carries to the posts or the walls on either side of the opening.
In the context of Gothic architecture, other structural elements like the flying buttress were developed to transfer weight loads and counter lateral forces, allowing for larger windows and higher walls, which are characteristic of the style.
The ingenuity of such architectural elements allowed for greater building heights and more expansive interior spaces, which were previously limited due to the heavy stone and wood materials used for construction.