Mullion in the context of "Lintel"

Rose window is often used as a generic term applied to a circular window, but is especially used for those found in Gothic cathedrals and churches. The windows are divided into segments by stone mullions and tracery. The term rose window was not used before the 17th century and comes from the English flower name rose.

The name "wheel window" is often applied to a window divided by simple spokes radiating from a central boss or opening, while the term "rose window" is reserved for those windows, sometimes of a highly complex design, which can be seen to bear similarity to a multi-petalled rose. Rose windows are also called "Catherine windows" after Saint Catherine of Alexandria, who was sentenced to be executed on a spiked breaking wheel. A circular window without tracery such as are found in many Italian churches, is referred to as an ocular window or oculus.

A portal is an opening in a wall of a building, gate or fortification, especially a grand entrance to an important structure.

Doors, metal gates, or portcullis in the opening can be used to control entry or exit. The surface surrounding the opening may be made of simple building materials or decorated with ornamentation. The elements of a portal can include the voussoir, tympanum, an ornamented mullion or trumeau between doors, and columns with carvings of saints in the westwork of a church.

Tracery is an architectural device by which windows (or screens, panels, and vaults) are divided into sections of various proportions by stone bars or ribs of moulding. Most commonly, it refers to the stonework elements that support the glass in a window. The purpose of the device is practical as well as decorative, because the increasingly large windows of Gothic buildings needed maximum support against the wind. The term probably derives from the tracing floors on which the complex patterns of windows were laid out in late Gothic architecture. Tracery can be found on the exterior of buildings as well as the interior.

There are two main types: plate tracery and the later bar tracery. The evolving style from Romanesque to Gothic architecture and changing features, such as the thinning of lateral walls and enlarging of windows, led to the innovation of tracery. The earliest form of tracery, called plate tracery, began as openings that were pierced from a stone slab. Bar tracery was then implemented, having derived from the plate tracery. However, instead of a slab, the windows were defined by moulded stone mullions, which were lighter and allowed for more openings and intricate designs.

A hexagonal window (also Melnikov's or honeycomb window) is a hexagon-shaped window, resembling a bee cell or crystal lattice of graphite. The window can be vertically or horizontally oriented, openable or fixed. It can also be regular or elongately-shaped and can have a separator (mullion).

Typically, the cellular window is used for an attic or as a decorative feature, but it can also be a major architectural element to provide the natural lighting inside buildings. The hexagonal window is relatively rare and associated with such architectural styles as constructivism, functionalism and, occasionally, cubism.

In architecture, a transom is a transverse horizontal structural beam or bar, or a crosspiece separating a door from a window above it. This contrasts with a mullion, a vertical structural member. Transom or transom window is also the customary U.S. word used for a transom light, the window over this crosspiece. In Britain, the transom light is usually referred to as a fanlight, often with a semi-circular shape, especially when the window is segmented like the slats of a folding hand fan. A prominent example of this is at the main entrance of 10 Downing Street, the official residence of the prime minister of the United Kingdom.

Perpendicular Gothic (also Perpendicular, Rectilinear, or Third Pointed) architecture was the third and final style of English Gothic architecture developed in the Kingdom of England during the Late Middle Ages, typified by large windows, four-centred arches, straight vertical and horizontal lines in the tracery, and regular arch-topped rectangular panelling. Perpendicular was the prevailing style of Late Gothic architecture in England from the 14th century to the 17th century. Perpendicular was unique to the country: no equivalent arose in continental Europe or elsewhere in the British-Irish Isles. Of all the Gothic architectural styles, Perpendicular was the first to experience a second wave of popularity from the 18th century on in Gothic Revival architecture.

The pointed arches used in Perpendicular were often four-centred arches, allowing them to be rather wider and flatter than in other Gothic styles. Perpendicular tracery is characterized by mullions that rise vertically as far as the soffit of the window, with horizontal transoms frequently decorated with miniature crenellations. Blind panels covering the walls continued the strong straight lines of verticals and horizontals established by the tracery. Together with flattened arches and roofs, crenellations, hood mouldings, lierne vaulting, and fan vaulting were the typical stylistic features.