Adam - According to the first book of the Old Testament, Adam was the first man. God formed him in his own image from the dust of the ground and gave him life by breathing the 'breath of life' into his nostrils. The name Adam derives from the Hebrew word for 'earth'.

Altarpiece - An image-bearing structure positioned on the rear of the altar.

Altar - A table or raised structure used for sacrificial, Eucharistic and other religious purposes.

Ammonia wax - A paste-like solution that causes swelling to the paint layer.

Apostles - From the Greek 'apostolos', meaning a person 'sent out' or 'messenger'. It was the name given to the twelve chief disciples and other early Christian missionaries who were charged with spreading the message of Christianity after Jesus' death and Resurrection.

Ascension - Jesus' return to Heaven at the end of his life on earth.

Barabbas - Barabbas was a robber released in preference to Jesus. Pilate initially tried to release Jesus, but the priests stirred up the crowd against him.

Bitumen - A dark brown, sticky, tar-like solution, used as brown paint from the 17th to 19th centuries.

Blistering - Raised areas of paint that have separated from the ground due to technique or unstable environment.

Caiaphas - Caiaphas was the High Priest before whom Jesus was interrogated. He found Jesus guilty and sent him to Pilate for sentencing.

Calvary - The place of the Crucifixion, also known as 'Golgotha', of which Calvary is a Latin translation.

Ciborium - A canopy usually supported by four pillars which covers the altar.

Communion - Another name for the Eucharist.

Conservation - A process of cleaning and stabilisation for objects including works of art.

Crucifixion - An execution performed upon a cross.

Diptych - A two-panelled altarpiece. These were often portable and for private devotional use.

Disciple - Meaning 'student', this word usually refers to the twelve men that Jesus chose to live and work with him.

Donor - Historically, this word referred to the person who commissioned the artwork from the artist. In a religious painting the donor may be portrayed kneeling in prayer as part of the scene. Hermann Rinck was the donor of the Master of the Aachen Altarpiece triptych. The word donor also refers to a person who donates artworks to a museum or any other institution.

Dossal - A horizontal painted panel, often composed of several panels joined together.

Encaustic painting - A method of painting with molten wax. Dry pigments are mixed with molten wax on a warm palette and then applied to a ground or surface.

Eucharist - From the Greek word for 'thanksgiving', it is the central Christian ceremony when bread and wine are eaten in church to signify the body and blood of Jesus. It also commemorates the Last Supper, the meal Jesus had with his followers.

Film - A thin layer or coating of paint.

Flaking - A loss of paint fragments.

Flanders - An ancient country that was situated between the borders of northern France and Germany, it now forms part of modern-day Belgium and Holland.

Gesso - A white coating used as a ground for painting, also used to prepare wood for gilding.

Gilding - The decoration of works of art and architecture with gold, silver or other metals.

Glastonbury - A town in rural Somerset, said to be the site of the first Christian church in England, it was also important to pagan druids. It now hosts an annual music festival.

Glaze - Used to cover a painted surface with a thin, transparent layer of colour.

Golgotha - The site of Jesus' crucifixion is named 'Golgotha', which means 'skull' in Aramaic.

Gothic Period - Used to describe a style of architecture characterised by pointed arches.

St. Gregory the Great - Pope from 590-604, he was the most important of the numerous saints called Gregory. Born around 540 AD he was the son of a Roman senator and the great grandson of a former Pope. He established a Benedictine monastery on his own estate, and in 597 AD sent the first Christian missionaries to Britain. Gregory was a prolific author and revised the Church liturgy and established Gregorian chant. He is one of the four Doctors of the Church, along with Augustine of Hippo, Ambrose and Jerome.

Ground - A layer coated onto the support to prepare the surface for the paint. Term used for the priming of an oil or tempera painting.

Holy Grail - The Holy Grail was a chalice in which Joseph of Arimathea was though to have caught Christ's blood. Some Christians believe Joseph brought it to Glastonbury, England and formed a church there.

Impasto - Paint that is applied thickly to a canvas or panel so that it stands out in relief, retaining the marks of the brush of palette knife.

Jerusalem - Originally established as capital of the ancient kingdom of Israel by King David around 1000 BC, it was enlarged and fortified by King Solomon who built its great Temple, of which the Wailing Wall is the last remaining remnant. Jerusalem became central to the Christian religion since it was the place where Jesus was crucified and buried.

Jesus Christ - Jesus was born around 4 BC and died around 30 AD. According to the Christian faith, Jesus is the eternal Son of God. Jesus is also known as Christ, Greek for the Hebrew word Messiah - 'the anointed one' - standing for the future (non-divine) leader of the Jewish people. The term Christ was later used by the Church to mean the saviour of humankind.

St. John the Evangelist - John the Evangelist is the traditional name given to the anonymous author of the fourth Gospel in the New Testament. The repeated reference in the work to the 'beloved disciple' has led many people to identify this as John, son of Zebedee, youngest of the original twelve disciples of Jesus. Evangelist is from the Greek for 'good news'.

Joseph of Arimathea - Joseph was a well-respected and affluent member of the Sanhedrin who gave his tomb for Christ's burial. He secured Pontius Pilate's permission to take the body of Jesus after the Crucifixion, and buried him with the help of Nicodemus.

Liverpool Royal Institute (LRI) - A permanent art gallery opened in 1817 with the help of William Roscoe (1753-1831). The work displayed in the gallery showed the rise of painting from the 14th to 17th centuries in Europe and much of it had once belonged to Roscoe. The Master of the Aachen Altarpiece wings appeared in the LRI catalogue in 1843.

St. Longinus - Roman soldier who pierced Christ's side with a lance, curing his own blindness and becoming a follower. His name comes from the Greek word for a lance.

The Virgin Mary - According to Christian faith, Mary conceived through the Holy Spirit of God and gave birth to Jesus. As Jesus' Mother she is an important figure for the Christian Church as a link between human kind and God.

Mary Magdalene - Mary Magdalene received her name from the village of Magdala, now in modern Israel. A reformed sinner, she once washed Christ's feet with her tears and dried them using her long hair. She was also the first person to see Jesus after his Resurrection, although she initially mistook him for a gardener.

Modelling - To create a three-dimensional effect using different shades and tones of paint.

Myrrh and Aloes - These were ointments used in the preparation of dead bodies. Aloes are bitter juices taken from the bark of the Agalloch tree, also known as eagle-wood. Myrrh is a gum resin from the plant Sweet Cicely that was used for making perfumes and incense.

Nicodemus - A Pharisee and member of the Sanhedrin, he was taught by Jesus secretly at night. Nicodemus also helped Joseph of Arimathea to bury Christ after the Crucifixion.

Oil painting - A method of painting using pigments dispersed in oil.

Pala - Italian term for a large altarpiece, a large, unified framed panel.

Panel painting - Painting on a wooden support.

Passion - From the Latin for 'suffering', this refers to Jesus' suffering leading up to the Crucifixion.

Passover - Passover is one of the chief religious festivals of the Jewish faith. It became linked to the story of the escape from slavery in Egypt, when God killed the first-born of the Egyptians, but 'passed over' the Israelites and granted their release. It is celebrated in early spring.

Patron - Owner or commissioner of a piece of art work. Hermann Rinck, mayor of Cologne, was the patron of the Master of the Aachen Altarpiece triptych.

Pentimento - Visible evidence of an alteration to a painting or drawing that indicates the artist changed their mind while executing the painting. This can leave an effect where 'ghosting' lines from the original design can be seen through the thinning paint.

Pharisee - The Pharisee were members of a strict traditionalist Jewish sect that was determined to uphold Hebrew law and ritual in everyday life. The name is Hebrew for 'interpreter'.

Pieta - This is Italian for 'lamentation' and is a term used to describe the scene immediately following the descent from the cross, in which mourners surround the body of Christ, stretched out on the ground.

Pigment - Fine powder (in a range of colours) that is bound with oil, yolk, or water in order to be used for painting.

Pontius Pilate - Pilate was Roman procurator of Judea from 26-36 AD. He presided over the trial of Jesus.

Polyptych - An elaborate structure made up of several vertical individual panels, often with wings.

Predella - A step or platform upon which an altar is placed.

Priming - A white paint layer used to prepare the support surface before painting.

Resin - Used to make varnishes.

Restoration - Repairing missing areas, retouching and painting them.

Roscoe - William Roscoe (1753-1831) was a self-educated lawyer and author, and campaigner against the slave trade. He promoted art education in Liverpool and helped form many of the cultural and scientific institutions in the city in the early 19th century, including the Liverpool Royal Institute. He formed a pioneering collection of early Renaissance Italian and north European paintings, drawings and prints, some of which were acquired for the LRI and are now in the Walker Art Gallery.

Salome - husband to Zebedee, mother to John and James, she was one of the 'Three Mary's' present at the Crucifixion. She may possibly have been Jesus' aunt.

Sanhedrin - The Sanhedrin were the council of Jews at Jerusalem. They had some powers of their own, although their decisions were subject to the approval of the governor, Pilate.

Stigmata - Wounds caused by crucifixion - holes in the hands and feet from nails.

Tempera - A painting medium used to bind pigments. By the 16th century the term was known as egg tempera, a paint that uses egg yolk as the binding medium.

Tonality - Softening and harmonising the colouring of a painting.

Triptych - A three-panel altarpiece, often with folding wings, that may be shut to cover the central panel for ceremonial purposes.

Varnish - A layer used to protect the paint layers of a painting, usually the cause of discolouring the paint.

Wing - A side panel of the altarpiece usually hinged to the adjacent panel.

Zebedee - Father of St John and James, two of the apostles.