Abbey
Although we might think of any large monastery as an abbey, and a nunnery as something else, the word 'abbey' actually refers to any large religious community (and its buildings) – whether lived in by monks or nuns – and ruled over by an abbot (a word originally meaning 'father') or abbess. The second-in-command in an abbey was the prior; so any monastery that was dependent on a larger, more important one was usually known as a priory.

Adze blade
One of a variety of stone tools designed for woodworking by our very ancient ancestors. An adze blade differs from an axe in that it is mounted on a shaft at a 90-degree angle. Probably used for stripping bark from timbers, which helps to create a smoother surface for sinking piles or posts and helps to preserve the wood by removing wood-boring creatures, moulds and fungi. See also handaxe.

Aerial photography
Photographs taken from the air are particularly useful to archaeologists, and not just because the view gives us a different perspective of a site or the landscape. At different seasons and at varying times of the day, much information can be learned about sites when they are viewed from the air.

In the winter – from, say, October to March – the sun is low in the southern horizon in the morning and afternoon; in December, January and February, the sun does not rise much above the horizon even in the middle of the day. At such times, earthworks and other bumps and lumps in fields – even very small ones, no more than a few inches high – will have a shadow and a highlighted side. Seen from the air, these can be more easily understood as forming a particular pattern, and therefore, this must be a certain sort of site. Earthworks are frequently very confusing at ground level, but from above, the general plan is much clearer, enabling archaeologists to suggest that they are the remains of a deserted medieval village, prehistoric settlement or whatever.

At other times of the year, other patterns can be identified from the air. Imagine you are a cat walking across a patterned carpet. From the level of the cat's eyes, it would be difficult to understand the layout of the pattern. But from the height of a human being, 1.5-2m (5-6ft) above the carpet, the pattern becomes clear.

When fields are ploughed, soil in which remains have been buried may, from the air, show up as differently coloured. Such soil marks – which may be barely appreciated at ground level – enable archaeologists to locate sites. More importantly, certain buried remains can create conditions that affect the growth of plants, and this can be seen from above. See cropmarks.

Ages
The terms 'Bronze Age', 'Iron Age' and so on are used by archaeologists as a convenient shorthand for discussing the chronology of the past. In reality, the changes from one period to the next would have been far more gradual than these sharp distinctions imply. For example, our prehistoric ancestors didn't stop using stone tools on 31 December 2301 BC and switch to bronze tools overnight!

The accepted dates for these periods also vary in different parts of the world, because different areas developed at different times. Middle Eastern and Mediterranean civilisations, for example, developed metalworking before people living in Britain, so that their Bronze and Iron Ages arrived earlier. See also Timeline.

Aisled hall
A building in which, as well as the main part of the structure, there are spaces along the sides, with the roof above usually supported on pillars. Sometimes these aisles, found in many medieval parish churches, were the result of expanding the original building by punching holes through the side walls but leaving pillars to hold up the remaining part of the walls above, or it was a way of roofing a large space with timbers that were not long enough to cover the full width. Because it was a common design in large medieval secular (ie not religious) domestic buildings, there is also probably an element of fashion in the design.

Anaerobic conditions
'Anaerobic' means 'without air'. In such conditions – such as waterlogging – where there is insufficient oxygen for bacterial and fungal growth, the normal rotting processes do not take place. So all the things made of wood, leather, straw and so on that archaeologists love to find, but which, in our climate, usually rot away very quickly, remain well preserved. Much can be learned from such evidence about the lives of ordinary people in the past; many of the objects they used and the structures and buildings in which they lived were made of wood. But such finds are a nightmare for the people who have to conserve them, since they have to stop these objects rotting once they are brought into normal – that is, aerobic ('with air') – conditions. See wood conservation.

Anglo-Saxons
'Anglo-Saxon' is used as a catch-all phrase to refer to the Germanic peoples who invaded and settled in England in large numbers during the fifth and sixth centuries AD. As well as the Angles (who came from the southern part of the Danish peninsula and eventually gave their name to England) and the Saxons (who came from the north German plain to the west), there were also Jutes (from Jutland) and smaller numbers from other Germanic tribes as well.

The removal of the Roman legions from Britain around 410 AD did not lead to an immediate Anglo-Saxon takeover. Nor did the newcomers invade as a single great force that defeated the native Britons. After the collapse of Roman authority in the early fifth century, centralised government broke down. Local rulers or strongmen moved to fill the gap. The earliest surviving account of the coming of the Anglo-Saxons (written two centuries afterwards) says that they were first hired as mercenaries, turning against their employers when they were not paid.

After that, there seem to have been great waves of migrating settlers, who soon established themselves in the southern and eastern parts of Britain. In some areas they may have driven out or enslaved the original British inhabitants; in others they may have coexisted peacefully. What is certain is that by 600 AD most of England had been reorganised into new small kingdoms ruled by Anglo-Saxon kings. Those Britons who were not subject to Anglo-Saxon rule had been pushed far into the west and north.

Anglo-Saxon Chronicle
One of the prime sources for the history of England during the so-called Dark Ages and Anglo-Saxon period, it purports to run from 494 to 1154 AD, the year of Henry II's accession to the throne. Much of the earlier material is probably folklore and hearsay, but from the 10th century onwards, it is very reliable. There are several versions of the Chronicle, since various monasteries kept annual accounts of what seemed to them the significant events of their time. Later chronicles – such as those of Henry of Huntingdon, Gervase of Canterbury, Ralph of Coggeshall, Ralph Diceto and Roger of Howden – continued the tradition into the Middle Ages.

Anglo-Saxon halls
The hall was the main domestic building in the period before the Norman Conquest, and indeed all through the Middle Ages. A vast barn-like building, it had few if any private areas, virtually no enclosed spaces, and few windows and doors. In the centre was an open fire, practically a small bonfire, whose smoke escaped through the roof thatch or out through a wooden louvre in the roof ridge. Halls served as courtrooms, administrative centres, social meeting places, eating and feasting rooms and, no doubt for many people, sleeping places as well. They are described in the 'Beowulf' saga of the Anglo-Saxon period, and though none of these wooden structures has survived, archaeologists using aerial photography can find traces of them in the form of cropmarks, or as post holes or trenches on excavation.

Anglo-Saxon palaces
Anglo-Saxon rulers were, like their counterparts in the Middle Ages, peripatetic – that is, they did not live in one place but moved around their kingdoms with their families, retainers, servants and officials, eating clean one area after another. They owned many estates, which were run in their absence by bailiffs or reeves. On many of these estates, there were what, for the time, would have been a very grand collection of halls (see Anglo-Saxon halls) and other buildings, which archaeologists have tended to call 'palaces', although they bore very little resemblance to such palatial residences as Buckingham Palace and Blenheim. The Anglo-Saxon palaces were built of timber, of which nothing has survived, but we should not assume from this that they were necessarily primitive. To judge from Anglo-Saxon metalwork and book illustration, they could have been highly decorated, carved and coloured, rather like the timber stave churches of Norway. Good examples of Anglo-Saxon palaces are known to have existed at Yeavering (Northumberland) and Malmesbury (Wiltshire), and at Cheddar (Somerset), where the foundations can be seen in the Kings of Wessex school.

Anomaly
The Oxford English Dictionary defines this as 'irregularity of motion, behaviour, etc.' In archaeology, an anomaly is an odd or unexpected feature not anticipated in the work being undertaken at the time. For example, at Much Wenlock Time Team's ground radar (see geophysics) showed what looked like walls and pillar bases, but when the Team excavated, these turned out to be cobbled surfaces and a well.

Apse
Early churches often had an apse – a semi-circular east end – to accommodate the altar. In Britain, this fashion lasted to Norman times, when many apses were replaced by square ends, although in the rest of Europe, quite a few churches retained their apses.

Armour
See Armour through the ages

Arthur
Perhaps the most famous name from the British 'Dark Ages' is that of King Arthur, of the legendary Camelot and the Knights of the Round Table. But in fact the whole story is an invention, created some six centuries after he was supposed to have lived by Geoffrey of Monmouth, who wrote a fictional account of the kings of England in the 1130s. For those seeking a historical Arthur there are just four scant references to anyone of that name in ancient documents. The rest is speculation and fantasy.

Asser
A priest from St David's in Wales who became the friend of Alfred the Great and wrote a biography of that king's deeds. Asser died in about 910.

Augering
An auger was once a primitive sort of drill, but nowadays it is, among other things, a device used by geologists and soil scientists to drill small samples from the earth for examination. Augers are also used by dendrochronologists to take cores of wood from trees or timbers. See dendrochronology.