"Tympanum" and "pediment" have definitions that seem to be very close, but I have yet to see them both used to refer to the same object in an actual text.

Pediment is defined as:

a triangular space that forms the gable of a low-pitched roof and that is usually filled with relief sculpture in classical architecture (Merriam-Webster)

Tympanum is defined as:

a. the recessed usually triangular face of a pediment within the frame made by the upper and lower cornices

b. the space within an arch and above a lintel or a subordinate arch (Merriam-Webster)

I've checked a few other dictionary sources, none of which, unfortunately, were clarifying.

So, I'm trying to understand exactly what the difference is here. Obviously, the definition of a tympanum incorporates the definition of a pediment, and seems to imply something about the facing surface within the pediment. But this doesn't do much to help me understand what a 'pediment' actually is and how the two differ. Indeed, the definition seems to imply that it is "[the] triangular space that forms the gable of a low-pitched roof," which in my mind's eye is an analogous definition as "[a] recessed usually triangular face [...] within the frame made by the upper and lower cornices."

The annotated diagrams I have found are unfortunately not helpful, and usually point to the region as a whole. Images of tympanums usually show a heavily decorated space, but most definitions strongly imply that this is not a requirement for something to be a 'tympanum', and most don't state this at all. Pediments appear much simpler in explanatory diagrams, with little to no decoration except perhaps around the cornices if present.

The fact that one definition references the other strongly implies the two are not the same, but are distinct entities. My current best guess is that the word 'pediment' includes the cornices and/or arch themselves as well as the space as a whole, where the word 'tympanum' specifically refers to the facing surface within the triangular area bounded by cornices or the edge of an arch.

Exactly which features of the space between the roof and the doorway are considered part of the pediment, and which are part of the tympanum? Does the etymology of these words shed light on how they should be interpreted?

  • 5
    I don't think either of these words is well known to lay people outside of the architecture field. You'd probably do best asking architects.
    – Barmar
    Jul 11, 2023 at 7:03
  • 1
    There isn't an architecture SE, but some art questions are answered on History SE (particularly if you relate it to Greek architecture or similar).
    – Stuart F
    Jul 11, 2023 at 8:22
  • While both answers below, which confirm your own assumptions, are correct, it should be noted that pediment is likely to be understood by a somewhat wider audience than tympanum, and is often used even when tympanum could be used.
    – jsw29
    Jul 11, 2023 at 20:12

2 Answers 2


According to J Henry Parker FSA in his 1836 Classic History of Architecture [adjusted slightly]:

Pediment: the triangular termination used in Classical architecture at the ends of buildings, over porticoes ... corresponding to a gable in the architecture of the Middle Ages. It is much less acute ... than a [typical] gable.

Most of the porticoes on the fronts of Greek and Roman buildings support pediments; in Roman architecture the dressings over doors and windows are sometimes arranged in a similar form, and are called by the same name. In debased Roman work pediments of this last kind are occasionally circular rather than angular on the top – a form also common in Italian architecture.

The term is also sometimes applied by modern writers to the small gables and triangular decorations over niches, doors, windows and the like, in Gothic architecture.

Tympanum: In Classical architecture, the name given to the triangular space between the horizontal and sloping cornices on the front of a pediment; it is often left plain, but sometimes covered with sculpture.

This term is also given to the space immediately above the opening of a doorway and the like in Mediaeval architecture, when the top of the opening is square and has an arch over it (not uncommon in Norman work); this type is usually ornamented rather than plain.

Also, when an arch is surmounted by a gable-moulding or triangular hoodmould, the space between the arch and the hoodmould is called the tympanum of the gable.


Wikipedia accords with my understanding of the terms:

Pediments are gables, usually of a triangular shape. Pediments are placed above the horizontal structure of the lintel, or entablature, if supported by columns. Pediments can contain an overdoor and are usually topped by hood moulds. A pediment is sometimes the top element of a portico. For symmetric designs, it provides a center point and is often used to add grandness to entrances.

The tympanum, the triangular area within the pediment, is often decorated with a pedimental sculpture which may be freestanding or a relief sculpture.1 The tympanum may hold an inscription, or in modern times, a clock face.

1 Sturgis, Russell (1896). European Architecture: A Historical Study. The New York Public Library: Macmillan. pp. 3, 558.


Perhaps you can think of the pediment and tympanum as a drum turned on its side. The pediment is the whole thing; the cornice the raised parts of the side of the drum which support the drum-skin, the tympanum — which may well be where the name typanum came from.

OED doesn't give a clear etymology for the architectural terms at all, even speculating that pediment is a corruption of pyramid.

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