'Megalith' means literally 'large stone'. The word is used for prehistoric monuments made from large stones, as well as for the stones themselves. Megalithic monuments are the most noticeable remains of the Stone Age and Bronze Age culture of Northwestern Europe.

Here are some of the terms used in describing megaliths, neolithic tombs and stone circles. Where the Irish terms differ from the UK ones, I'll try and point it out.

• Alignment - when two or more stones line up with some distant object or with some astronomical event on a particular day. The most common are sunrise or sunset on the solstices, equinoxes or the quarter days (half way between solstice and equinox). Occasionally lunar risings and settings are aligned, but the moon is more variable - moonrise positions vary over a cycle of 17 years. There's a table of possible solar alignments at the end of this entry. Three or more stones in a row may be referred to as an 'alignment' even though they don't line up with anything in particular on the horizon, but the more usual term for this is 'stone row'.

• Barrow - a mound built over a burial. This word is used in Ireland for Bronze Age burial mounds where there is no entrance into the burial chamber. Stone Age mounds always had a doorway and are not considered to be barrows. In the UK, the word barrow can mean any sort of an artificial hill over a burial.

• Bullaun or bullán - this is a cup-shaped hollow in a boulder which generally fills up with rainwater. In Early Christian times, these were often considered to have been made miraculously by saints, and miracle cures were attributed to the water from the bullaun. A good example is station 7 of the Stations of Saint Brigit in Faughart, Co Louth, Ireland. It is a stone with two bullauns side by side, and is said to be made by the knees of Saint Brigit as she knelt in prayer.

  Bullauns in fact predate Christianity. One theory as to their original use is that druids (pagan priests) would put stones in the holes, and would turn the stones while reciting a curse against their enemies. The turning of the stone made the curse stronger. Some bullauns still have a stone sitting in them.

  
  They loosed their curse against the king;
  
  They cursed him in his flesh and bones;
  
  And daily in their mystic ring
  
  They turned the maledictive stones
  
  — Samuel Ferguson, The Burial of King Cormac

• Cairn - an artificial hill made from small stones and rocks.

• Chockstones are small stones placed under one end of a recumbent stone so that the top of it will be level.

• Circle henge - a henge with a stone circle in it

• Cist - pronounced 'kist' and sometimes spelled that way, this is a very small grave, a cube with sides of about a half metre (1 foot 6 inches), with flat stone sides and one on top, which is then covered over with a mound. The corpse may be cremated and the ashes places in the cist, sometimes accompanied by an urn, or the body may be stuffed into the grave - the limbs of the body often had to be broken to fit it in.

• Concentric circle - a form of monument in which there are two stone circles, one inside the other, sharing a common centre.

• Corbelling - a form of roof construction for the chamber in a tomb covered by a mound. Almost-horizontal flat stones are placed above the side walls, projecting a small distance over the chamber. Then another layer of flat stones is placed on these, projecting further. This is continued until the whole chamber is covered. Corbelling is used anywhere that the chamber is to wide to be covered by a single slab.

• Court Tomb - an elaborate type of burial mound found mainly in Scotland and the northern third of Ireland. The mound has a stone-lined chamber inside which opens directly through a portal-style doorway (two upright stones and an lintel) onto a flat outdoor area known as the 'court'. The mound stretches around the court on both sides of the doorway and the sides of the mound facing the court are normally faced with large standing stones. In some cases, the mound almost completely surrounds the court, leaving just a narrow passageway into it which was presumably open to the sky at the top.

• Cove - the Cove is a group of three standing stones in Stanton Drew, Somerset, England, which is also the site of the second largest circle in Northwestern Europe. The word Cove is sometimes used to describe similar structures in other locations. The Cove consists of three large stones which are placed on three sides of a rectangle, with flat sides facing into the rectangle. The stones are spaced widely apart, not meeting at the corners. The Cove appears to mark out a ceremonial space.

• Dancers - many stone circles, particularly in England, have names with the word 'dance' in them. Stonehenge itself was once known as the Giants' Dance. This is because of the mediaeval legend that such circles were people who had been turned to stone during the act of dancing, perhaps on a Sunday. Often an outlying stone is known as the 'piper' for the same reason.

• Erratic - an erratic is a geological feature rather than a man-made one. It is a large stone or boulder which is of a different type of rock to the ground on which it stands. These are carried to the area by glaciers or ice sheets during an ice age. When the ice melts, the rock is left behind. Builders of stone circles often used erratics, giving the impression to modern researchers that they carried the rocks for large distances.

• Flankers are the tall stones in a Scottish recumbent circle that stand on either side of the recumbent stone, usually touching it.

• Four poster - a type of 'circle' consisting of just 4 stones. Sometimes these are all the same size and form a rectangle, but not often.

• Grading - the positioning of stones so that they increase in height from one side of the circle to the other. Irish recumbent stone circles are often graded upwards from the recumbent to the portals at the other side which are the tallest stones. The stones in a Scottish recumbent stone circle, on the other hand, are graded so that they decrease in size from the flankers on either side of the recumbent down to the smallest being opposite the recumbent.

• Henge - a circular bank with a ditch inside. The soil from the ditch is piled up to form the bank. Henges are considered to be ceremonial features rather than defensive ones because you would put the ditch on the outside if you intended it to repel attackers. The word henge comes from the name Stonehenge, but ironically, Stonehenge is not a typical henge because the ditch is outside the bank. The term henge-like structure is used for an earthbank which appears to be ceremonial rather than defensive but differs in some way from the classic henge.

• Kerb stones - stones which are set into the base of an artificial hill such as a passage tomb, so that one side is visible and the other is inside the hill. Sometimes the hill is removed over the millennia (usually as a source of building stone) but the kerb stones remain, leaving a circle of stones which is not really a 'stone circle'.

• Leaning stone - a stone which was intended to lean by the builders rather than one that is in the process of falling down. These are rare in Ireland.

• Megalith - a construction made from big stones, or sometimes just a big stone itself.

• Mesolithic - the Middle Stone Age, in which people lived by hunting and gathering, and did not construct any large monuments out of stone.

• Neolithic - the New Stone Age, in which people lived by farming but without any form of metal. The construction of megaliths began in the Neolithic period but continued into later periods such as the Bronze Age.

• Orthostat - a stone or slab which is standing straight up.

• Outlier - a stone which stands outside of a circle.

• Passage Tomb - a very early type of Neolithic tomb. A giant mound is made from stones and soil. Set into this mound are one or more passages, which are generally straight, lined with stone slabs and open into a chamber. The chamber may be circular and may have burial recesses around its edges. Often there are three recesses, arranged so that the passage, chamber and recesses form the shape of a cross. The passages are often positioned so that they align with some significant astronomical event such as the rising of the sun on the Winter Solstice. Passage tombs are normally built at the tops of hills so that they are visible from far off, and were constructed in the New Stone Age (Neolithic) from about 4000 BC to about 2000 BC.

• Portal stone - one of a pair of stones which appear to form a ceremonial entrance into a tomb or stone circle. This may be because they are taller than the others, or they may be flat stones with the flat sides facing each other, while the other stones have their flat sides facing the centre of the circle. In some circles, particularly in northwestern England, the portals are a separate pair of stones just outside the circle.

• Portal Tomb - also known as a dolmen, portal dolmen, cromlech or quoit, this is a simple tomb consisting of four main stones with a few smaller ones. There are two tall upright stones known as portal stones and a third which is lower, forming a triangle. A giant capstone is placed on top of the three stones so that it covers the whole tomb. Due to the differing heights of the uprights, the capstone is sloped. The gaps between the uprights are normally filled in with flat stones to form a chamber, but in many tombs these stones are no longer in place. Unlike other Neolithic tombs, portal tombs do not appear to ever have been covered by a mound.

• Postholes - examination of the ground around megalithic monuments sometimes shows cylindrical holes which have been dug and then later filled in. It is assumed that these contained wooden posts. In some cases the posts appear to have been part of a structure, such as a round house. In others, particularly in Stonehenge, it appears that a number of posts were erected to test out the astronomical alignments before positioning the large stones.

• Prostrate - a stone that was originally vertical but has fallen over, as opposed to a recumbent which was placed lying down in the original design. For example, the so-called 'slaughter stone' in Stonehenge, long considered to be a sacrificial altar, is actually a prostrate stone, one which was originally a standing stone.

• Rath - in Ireland there are about 40,000 circular earthbanks known as raths¹ which were defensive structures - they are the remains of ancient farms, where the ring was topped with a fence and there is evidence of buildings in the ring. Most of the raths survived until recent times because of the belief that they were the homes of the Shee (fairies), malicious supernatural creatures. It was thought that disturbing a rath would bring bad luck. Sadly, as the belief in the Shee has disappeared, many of these raths have disappeared under the plough.

• Recumbent - the low, wide stone of the recumbent stone circle.

• Recumbent stone circle - a very common type of circle with a number of upright stones in a circle and one stone which is horizontal (recumbent) - that is, wider than it is high. These can be divided into Irish (mainly from Cork and Kerry) and Scottish.

• Sarsen - a type of rock. Because the biggest stones in Stonehenge and Avebury are made of sarsen, these are often called sarsens.

• Standing Stone - a stone which is taller than it is wide and has been placed in position by slotting it into a hole in the ground.

• Stone row - a series of stones in a straight line, usually evenly spaced, which are sometimes constructed in the same locations as stone circles, particularly in Northern Ireland.

• Trilithon - literally 'three stones', this is a construction which occurs in Stonehenge - two identical standing stones with a third stone placed across the top of them as a lintel. Stonehenge has a horseshoe shape of five of these trilithons at the centre of the circle.

• Wedge Tomb - a type of Neolithic tomb found only in Ireland, built in the last part of the Neolithic Age. It is like a very small passage tomb, with a very low and narrow passage about a metre wide and a metre high with walls and ceiling of stone, which was then covered in a mound which was the shape required to cover the passage rather than a giant round hill. There is an entrance into the passage at one end. The burial chamber is not a separate room but merely the other end of the passage fenced off by a slab or a low sill. The passage normally tapers slightly, hence the name 'wedge'. The mound over the tomb can be as low as a metre high and the whole tomb, mound and all may be as small as 5 metres in diameter, compared with 80 metres for the biggest passage tombs. Wedge tombs are normally made so that the portal faces west, and are built on the sides of hills rather than at the top. In most cases, the mound has disappeared over the years but the sides of the chamber are still intact and the structure is usually known by the name 'The Giant's Grave'.

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Table of Alignments

Note: the solstics alignments are approximate. At the latitude of Stonehenge they are within 1 degree of correct, but as you get away from this latitude they will vary.

If the passage of a passage tomb points in a particular direction, then that is the direction of the alignment. But if a row of stones points in a direction, then it also points in the opposite direction, so a Northeast alignment is also a Southwest alignment.