Lexicon

Celtic /ˈkɛltɪk/ - pertaining to the Celts, their culture, or their languages, which constitute a branch of the Indo-European family and include Irish, Scottish Gaelic, Welsh, Breton, Manx, Cornish, and many extinct pre-Roman languages such as Gaulish and Galatian.

Celtic knot - any of a variety of knots and stylized graphical representations of knots used for decoration, used extensively in the Celtic style of Insular art.

Druid - a member of the high-ranking class in ancient Celtic cultures, often serving as a religious leader, legal authority, adjudicator, medical professional, or political advisor. While they were reported to have been literate, druids left no written accounts as they are believed to have been prevented by doctrine from recording their knowledge in written form.

Hallstatt culture - the predominant Western and Central European culture of the late Bronze Age (c. 1200 BC - 700 BC) and early Iron Age (c. 700 BC - 500 BC), developing out of the Urnfield culture of the 12th century BC and followed in much of its area by the La Tène culture. It is commonly associated with Proto-Celtic populations.

Insular illumination - the production of illuminated manuscripts in the monasteries of Ireland and Great Britain between the 6th and 9th centuries, as well as in monasteries under their influence on continental Europe. It is characterized by decoration strongly influenced by metalwork, the constant use of interlacing, and the importance assigned to calligraphy.

La Tène culture - (c. 450 BC - 50 BC) replaced the earlier Hallstatt culture as the dominant culture of central Europe, especially in terms of art, and later went into decline following the conquest of Gaul by Julius Caesar. Artifacts of the La Tène culture have been discovered in a wide arc covering western and central Europe, spanning from Ireland to Romania.

Lugh - a prominent Celtic deity, also known as Lugus in Britain and the European mainland, or as Llew Llaw Gyffesin Wales, who was principally associated with skill and kingship but often also connected with light or the sun.

Ogham /ˈɒɡəm/ - an ancient alphabetical writing system used by the Celts in Ireland and Britain, consisting of straight lines drawn or carved perpendicular to or at an angle to another long straight line.

Oppidum /ˈɒpɪdəm/ - an ancient fortified town built by the Celts in Central Europe between 200 BC and 100 AD as conflicts arose with Roman culture following increased competition for land and resources.

Triquetra /traɪˈkwɛtrə/ - a triangular figure composed of three interlaced arcs, or (equivalently) three overlapping vesicae piscis lens shapes. It is used as an ornamental design in architecture, and in medieval manuscript illumination (particularly in the Insular tradition). Its depiction as interlaced is common in Insular ornaments from about the 7th century. In this interpretation, the triquetra represents the topologically simplest possible knot.

Urnfield culture - (c. 1300 BC – 750 BC) a late Bronze Age culture of Central Europe, often divided into several local cultures within a broader Urnfield tradition. The name comes from the custom of cremating the dead and placing their ashes in urns, which were then buried in fields. Over much of Europe, the Urnfield culture followed the Tumulus culture and was succeeded by the Hallstatt culture. Some linguists and archaeologists have associated this culture with the Proto-Celtic language, or a pre-Celtic language family.

Vesica piscis - a type of lens, a mathematical shape formed by the intersection of two disks with the same radius, intersecting in such a way that the center of each disk lies on the perimeter of the other.

Votive offering - one or multiple objects displayed or deposited, with no intention of recovery or use, in a sacred place for religious purposes. Such offerings are practiced in both modern and ancient societies and are generally given in order to impress or win favor with supernatural forces.