Pendentive: one of the four triangular, concave members that convert a square space into a circle for the support of a dome. Their apexes rest on the four piers at the angles of the square, and, as the triangles arch inward, their bases unite in a circle.
Peripteral (lit. “winged-around”): designating a temple, when the cella is surrounded by a single range of columns. Compare Pseudo-peripteral.
Peristyle: a system or range of Columns, specifically surrounding a temple or court. See Colonnade.
Piano nobile: Italian term for the principal story of a building. Compare French Bel Étage.
Pier: a vertical supporting member, other than a column or pillar.
Pilaster: a square column, projecting about one-sixth of its width from the wall, and of the same proportions as the Order with which it is used.
Pinnacle: a small turret-like termination; especially at the top of buttresses to increase their weight and capacity of lateral resistance.
Plate Tracery: See Tracery.
Plinth: specifically, a block, usually square, which forms the lowest member of the base of a column. Generally, the block on which a column, pedestal or statue rests.
Podium: a wall supporting a row of columns; specifically, in Roman architecture, the temple platform that does not project beyond the line of the columns as does a Stylobate (which see).