Oak
One of the principal building materials used in the past, especially for roofs and for major structural timbers. The dating method known as dendrochronology has so far been developed mainly for this wood.

Offa's Dyke
A great linear earthwork consisting of a bank with a ditch on the western side, which runs from Prestatyn, Clwyd to Chepstow, Gwent, straddling the border between the Welsh and the English. It was built in the reign of Offa, king of Mercia (in the north Midlands) in the late 8th century. About 80 miles of the original 120 still survive. See also dykes.

Ogam/ogham
An early script developed in Ireland whereby letters are rendered as cut marks in the edge of a stone. Several strokes are used to indicate each letter. It was used in the so-called Dark Ages, particularly between the 5th and 9th centuries. The letters were usually carved on memorial stones so are found in churches and graveyards, particularly in Ireland, Wales, Scotland and south-west England. We know what the ogam marks mean because the message is usually repeated in Latin, which can then be translated.

Osteoarchaeology
Osteoarchaeology is the archaeology of bones. The study of bones found in archaeological excavations tells us a great deal about the past. From the study of animal bones found in archaeological contexts we can learn much about ancient diets, agricultural and social practices. And from the study of human skeletal remains we can answer all sorts of questions about how people lived, their health, the demographic profile of ancient populations and so on. The study of an individual's remains can tell us about that person's age, gender and stature, as well as their overall state of health and any diseases they may have suffered from. Conditions that can be identified by osteoarchaeology and reveal a lot about both individuals and the societies in which they lived include osteoarthritis, leprosy, venereal disease, tuberculosis and dental disease. Fractures or other wound marks can reveal how someone died – or disabilities that afflicted them during life.