See also the ALTAR CANOPY article.
The canopy, in general, is a decorative covering of fabric, stone, wood or metal, used to crown an altar, throne, pulpit, statue, etc. In liturgical language, the term is commonly used to designate
(a) the structure that covers an altar, previously provided with curtains and supported by four pillars;
(b) the cover suspended over the throne occupied by the dignitaries of the Church or princes;
(c) the covering under which the Blessed Sacrament is sometimes carried in processions, etc. (N. of the T.: This one is now called a canopy).
In the Middle Ages, altars were protected with a cover that was then called a ciborio (N. de la T.: Now the ciborium is called a ciborium), but which is now known as a baldachin or canopy that survives today as a characteristic of certain styles of architecture. As a sign of distinction, bishops and superior prelates are entitled to a covering on the thrones they occupy in certain ecclesiastical functions. This is called a canopy. It is sometimes granted by special privilege to prelates below bishops, but always with limitations as to the days on which they can be used and the character of their ornamentation. When the bishops attend solemn functions in the churches of regulars, they are obliged to place a canopy over the episcopal seat (Cong. de Ob. y Reg., 1603). The princes enjoy similar privileges, but their seats must be outside the sanctuary, and regulated according to custom.
The color of the canopy must correspond with that of the other clothing. Two types of canopies are used in processions with the Blessed Sacrament. One of small dimensions and in the shape of an umbrella – except that it is flat and not conical – and is called an ombrellino (pavilion). It is provided with a long stick with which it is supported. The other, called a baldachin, is more elaborate in structure and consists, in its main design, of a rectangular frame of rich cloth, supported by four, six or eight rods, with which it is carried. In both cases, the cover consists of gold cloth, or white silk. The canopy is used to carry the Blessed Sacrament to the sick and for transportation from the altar to the baldachin. The latter is used for all public processions, when carried by nobles of the highest rank, the most worthy carrying the most important staves. It is forbidden to carry the relics of the[[Communion of Saints|saints]under the canopy, but this honor may be given to those of the Holy Passion (Sag. Cong. Rit. May 1826).
Bibliography: Cæremoniale Episcoporum, (Rome, 1902), passim: Du CANGE, Glossarium Latinitatis, s. vv. Conopeum, Ciborium, Baldachinum (Venice, 1738); PUGIN, Glossary of Ecclesiastical Ornaments, sv Canopy (London, 1868); BOURASSÉ Dictionnaire d’archéologie sacree, sv Baldaquin (Paris, 1851); KRAUS, Geschichte der christlichen Kunst (Freiburg im Br., 1896), I, 372 etc.
Source: Morrisroe, Patrick. “Canopy.” The Catholic Encyclopaedia. Vol. 3. New York: Robert Appleton Company, 1908. Feb. 26, 2012
http://www.newadvent.org/cathen/03297c.htm
Translated by Luz María Hernández Medina.
Source: Catholic Encyclopedia