druid A priest of the Celtic people who spread across northern Europe and into the British Isles a few centuries BC. Archaeological artefacts excepted, most of what is known about them and their religion comes from classical Greek and Latin authors.
drystone (walling) Stone built up without mortar.
dyke or dike A ditch (occasionally to conduct water) or an embankment to keep water off land. The ambiguity stems from the fact that the two usually go together, for obvious reasons.
ecliptic The (mean) apparent path of the Sun through the stars, covered in the course of a year. The constellations through which the ecliptic passes define the traditional zodiac, but most of the familiar constellations in that band are of Middle Eastern origin, and are probably not prehistoric.
equator (celestial) The great circle in the heavens midway between the celestial poles. Poles and equator are determined by the Earth’s rotation, and the terrestrial equator is in the same plane as the celestial. See also equinox.
equinoctial See equinox.
equinox Loosely speaking, the time of year (spring or vernal equinox, autumnal equinox) when day and night are of equal length. These are the times when the Sun is on (or nearly on) the celestial equator, which is therefore sometimes called the equinoctial.
extinction altitude The altitude of a star below which it is invisible. This depends on various factors such as the brightness (magnitude) of the star and atmospheric conditions.
false portal See chamber tomb.
fiducial Regarded as a fixed basis of comparison (said of a line, point, or other marker).
flint A hard stone, usually steely grey or brown in colour, found in pebbles or nodules within a white incrustation. A relatively pure native form of silica, if suitably struck (knapped) it flakes so as to form (or leave) a sharp cutting instrument. Used for arrowheads, blades, scrapers, adzes, etc.
forecourt See chamber tomb.
gallery grave A chambered tomb in which the entrance passage, running into the burial chamber, is hardly (or not at all) distinguishable from it. There may be side chambers (as in the Severn–Cotswold type).
glaciation An Ice Age, the condition of being covered with an ice sheet or glaciers.
gnomon An upright (for example a stone or post, or later of finely contrived metal) from whose shadow time is estimated. Hence gnomonics, the science of calculating sun-dials.
gnomonics See gnomon.
grooved ware See Rinyo–Clacton.
heliacal rising/setting The rising of a star or group of stars just before sunrise, or the setting of the same just after sunset. See Appendix 4.
henge Circular banked enclosure with internal or external ditch and often one or more internal rings of timbers or stones. (This generic term is used in different ways by different writers, but ultimately derives by analogy with the name of Stonehenge.)
hillfort Hilltop defended by walls of stone, banks of earth, palisades of timber, ditches, or a mixture of these. Whether Neolithic causewayed camps had a defensive function is a moot point, but hillforts are usually taken to have been a late Bronze Age development, and most known examples date from the Iron Age.
hippodrome A course or circuit for horse-races or chariot-races.
Iron Age The period from say 700 BC onwards (the date varying from region to region) when iron had become the chief metal used for tools and weapons. (Bronze and flint continued in use, however.)
kerb Piled up stones forming a retaining wall around a mound. Kerbs may be internal or external and visible.
kist See cist.
leptolith Literally a slender stone. The word is used of slender flint cutting tools.
ley The name given by A. Watkins (around 1921) and his followers to certain alignments of natural and man-made objects that many of them believe follow the lines of certain unspecified kinds of force or energy emanating from the terrain. Their leys typically take in prehistoric, medieval, and even much more recent sites. An interest in leys was revived with the UFO craze in the 1960s.
libation The pouring out of wine or other liquid, whether or not conceived as a drink, in honour of a god or ancestor.
limb (of the Sun or Moon) The edge of the apparent disc of the Sun or Moon.
lintel A horizontal stone or timber, placed across the top of two uprights, as in a door frame.
long barrow See barrow
lozenge A rhomb, a geometrical figure in the shape of the ‘diamonds’ on playing cards.
lynchet A terrace cut into the slope of a (usually chalk) down, intended for cultivation.
magnetic flux A measure of the magnetism crossing a surface. More precisely: the surface integral of the product of the permeability of the medium and the magnetic field intensity perpendicular to the surface.
magnetometer An instrument for measuring the strength and direction of a magnetic field, in archaeology usually the Earth’s.
magnitude (of a star) A measure of the brightness of a star or planet. The Greek astronomer Hipparchus (second century BC) grouped stars on a scale from first (brightest) to sixth magnitude (barely detectable). It was eventually realized that the physiology of the eye is such that each step corresponds to a roughly similar brightness ratio. In 1856 N. R. Pogson established a standard scheme in which a difference of 5 in magnitude corresponds to a brightness ratio of 100 to 1. A difference of 1 in magnitude then corresponds to a brightness ratio of 2.512 to 1. The only magnitudes relevant to this book are magnitudes apparent to the eye. (Other definitions relate to the intrinsic luminosities of stars and to the type of radiation received by the detector.) marl A soil comprising a mixture of clay and lime.
megalith A large stone (by implication, one that is thought to have had a monumental use). (From Greek mega, large, and lithos, stone.)
Megalithic Yard (MY) A unit of length (0.829 m or 2.72 ft) that was used, according to Alexander Thom, in the construction of stone rings and other megalithic monuments.
menhir A single standing stone of appreciable height (a Breton word, said to be from men, stone, and hir, long). The word occurs in many Breton place names, but seems to have entered archaeology only in the eighteenth century.
meridian The plane containing the northernmost and southernmost points of the horizon, the north celestail pole, and the zenith overhead; or that part of the great circle on the celestial sphere through the last three points. (From the Latin meridies, midday, when the Sun crosses the meridian.) The word is also used of the terrestrial counterpart of this, namely a line of longitude on the Earth, as in ‘the meridian of Greenwich’. See culmination.
Mesolithic The period between the end of the last Ice Age (say 8000 BC) and the introduction of farming and pottery making (in Britain around 4500 BC).
Metonic