The gremiale, also called gremial, is an apron-like vestment worn by the bishop as part of the Catholic Mass or other sacred orders. The Catholic Encyclopedia describes the current understanding of this vestment in this way:
A square or oblong cloth which the bishop, according to the “Cæremoniale” and “Pontificale”, should wear over his lap, when seated on the throne during the singing of the Kyrie, Gloria, and Credo by the choir, during the distribution of blessed candles, palms or ashes, and also during the anointments in connection with Holy orders. The gremiale is never used during pontifical Vespers. The primary object of the gremiale is to prevent the soiling of the other vestments, especially the chasuble. The gremiale used during the pontifical Mass is made of silk. It should be decorated by a cross in the centre, and trimmed with silk embroidery. Its colour must correspond with the colour of the chasuble. The gremiales used at other functions are made of linen, to facilitate their cleansing in case they be soiled. Little is known of its history; apparently its origin dates back to the later Middle Ages. The Roman Ordo of Gaetano Stefaneschi (c. 1311) mention it first (n. 48); soon after it is mentioned in the statutes of Grandison of Exeter (England) as early as 1339, In earlier times it was used not only any bishop but also by priests. It is not blessed and has no symbolical meaning. ((http://www.newadvent.org/cathen/07026a.htm))
This is an intriguing vestment, particularly since “little is known of its history.” So I did some research and found a bit more about it.
First, this vestment is referred to explicitly as an “apron” in many references. The New Catholic Dictionary describes it:
A silken apron, trimmed with silk embroidery, of the color of the day laid upon the bishop’s lap when he sits during a pontifical Mass. A linen gremial is used when conferring sacred orders. ((http://saints.sqpn.com/ncd03744.htm))
Small golden laced, ornamented apron used when seated or conferring Holy Orders. ((http://www.memorare.com/puzzles/vestmentanswers.html))
The JM Latin-English Dictionary defines the term:
apron/lap cloth for bishop at Mass/pontifical functions
In Latin, the word gremiale literally means apron, derived from the Latin word gremium for lap, bosom, or womb ((http://www.answers.com/topic/gremial)). It is also called a lap cloth ((Addis, William E., Thomas Arnold, and T. B. Scannell. A Catholic Dictionary: Containing Some Account of the Doctrine, Discipline, Rites, Ceremonies, Councils, and Religious Orders of the Catholic Church. [Whitefish, MT]: Kessinger, 2006. 400. Link.)). Because of its relative word germe, it also happens to be the word used for firewood, or more generally for trees or shrubs ((http://dictionary.babylon.com/gremiale; http://www.myetymology.com/latin/gremiale.html; Whitney, William Dwight. The Century Dictionary; An Encyclopedic Lexicon of the English Language. New York: The Century co, 1889. 2620. Link.)).
The Century Dictionary notes that it is used by the bishop during mass or ordination “to protect his vestments from the consecrated oil” ((ibid.)). Or as another source puts it, “used in ordination to protect the sacred vestments from any drops of unction that might fall in the act of anointing candidates for the priesthood” ((Lee, Frederick George. A Glossary of Liturgical and Ecclesiastical Terms. London: B. Quaritch, 1877. 143. Link.)). It also seems that the gremiale is used to protect the vestments from being soiled from the sweat of the hands while sitting ((Rock, Daniel, George Waldegrave Hart, and Walter Howard Frere. The Church of Our Fathers As Seen in St. Osmund’s Rite for the Cathedral of Salisbury : with Dissertations on the Belief and Ritual in England Before and After the Coming of the Normans. London: J. Hodges, 1903. 336. Link)).
Most sources note how the gremiale is of different colors, and is usually highly decorated, embroidered with gold and silver thread. In most of the examples I found, this is true. Here are three: ((Thesaurus del Corredo Ecclesiastico di Culto Cattolico, “Gremiale,” http://126.96.36.199/thesaurus/struttura_gerarchica/index.jsp?ger=01.01.04.08.14&idnews=3130))
The gremial was originally made out of linen, but over time was gradually replaced with silk, or even the same material as the rest of the liturgical vestments ((Dolby, Anastasia. Church Vestments: Their Origin Use, and Ornament, Practically Illustrated. London: Chapman & Hall, 1868. 151-152. Link.)). Some have compared the gremiale to the towel girded by Christ as he washed the feet of the twelve apostles; indeed, it is still used in such feet washing ceremonies ((Bishop Mark A. Pivarunas, CMRI, “The Liturgy of Holy Week,” http://www.cmri.org/95prog4.htm; Catholic Church, and Joseph Rosati. Ceremonial for the Use of the Catholic Churches in the United States of America. Philadelphia: H.L. Kilner, 1894. 360. Link)). Although now primarily used by the bishop, the gremiale was originally used by all degrees of priesthood, including the prelate, priest, deacon and sub-deacon to cover the knees during Mass ((Dolby, Anastasia. Church Vestments: Their Origin Use, and Ornament, Practically Illustrated. London: Chapman & Hall, 1868. 151-152. Link.)).
Some sources note that this vestment was a type of “liturgical veil,” and was one of the vestments donned as part of a clothing ceremony ((Stravinskas, Peter M. J. Our Sunday Visitor’s Catholic Encyclopedia. Huntington, Ind: Our Sunday Visitor Pub, 1998. 478. Link; Baldeschi, Giuseppe, and John Duncan Hilarius Dale. Ceremonial According to the Roman Rite. London: Catholic Pub. & Bookselling Co, 1859. 89. Link)).
One of the most unique gremiales I found was that which belonged to the Archbishop Juan de Zumárranga, and is noted as the “oldest known embroidery in colonial Latin America” according to The Arts in Latin America, 1492-1820 ((Rishel, Joseph J., and Suzanne L. Stratton. The Arts in Latin America, 1492-1820. Philadelphia Museum of Art series. Philadelphia, PA: Philadelphia Museum of Art, 2006. 169. Link.)). This gremiale is particularly unique because it is so covered in symbols, in contrast to the definition given above that gremiales had “no symbolical meaning”:
The gremial’s design is similar to that of earlier Spanish ceremonial cloths. It is embroidered on blue velvet with gold and silver metallic and red silk threads and white silk appliques. The text around the border reads ARMA MUNDI REDEM / TORIS REGIS REGUM / UNIVERSI CREATORIS / IHVXPI SALVATORUS (The arms of the Redeemer of the World, King of Kings, Creator of the Universe, Jesus Christ the Savior). The shield in the center contains the cross and instruments of the Passions surrounded by a decorative foliate design and knotted Franciscan cords representing the order’s vows. In the four corners are shields with the five bloody wounds of Christ, part of the Fransciscan coat of arms, surrounded by decorative borders. ((ibid.))
One commentator thinks that the gremiale may “owe its origin to the Limus of the Victimarii” ((Pinnock, W. H. The Laws and Usages of the Church and the Clergy. 1855. 921. Link.)). In a footnote he quotes Fosbroke:
Limus, Limum, Limocincti – An Apron descending from the navel to the ankles, commonly bordered with purple. It was the only Vestment of the Victimarii. It was interwoven with many colours, and was called Licium, when worn by the servants of Magistrates, who were called Limocincti. ((ibid.))
This limus is an interesting word, by itself. It is the Latin word that describes the apron worn by a sacrificing priest, or by attendants of a sacrifice in ancient Rome ((Key, Thomas Hewitt. A Latin-English Dictionary Printed from the Unfinished Ms. of the Late Thomas Hewitt Key. Cambridge: The University press, 1888. 376. Link; http://www.myetymology.com/latin/limus.html)). The limocinti were “certain priestly officers who attended on a magistrate, as girt with an apron (limus)” ((ibid.)). These victimarii were those persons designated to perform the animal sacrifices ((http://www.mariamilani.com/ancient_rome/sacrifices_in_ancient_rome.htm; http://en.wikipedia.org/wiki/Religion_in_ancient_Rome)).
Many more modern examples of the gremiale can be found on the Cattolici Romani forum.
One of the best studies I’ve read about such aprons is Matthew Brown’s “Girded about with a Lambskin,” in the Journal of Book of Mormon Studies 6:2 (1997), p. 124-151. His analysis includes a look at such ritual apparel in ancient Israel, Egypt, Mesopotamia, among the Freemasons, and in the Book of Mormon.