Key terms & definitions

The reaction in which reactants form products as the equation is written from left to right.

The reaction that converts reactants into products, read from left to right in a chemical equation.

Vertical integration towards a later stage of the supply chain, such as a manufacturer taking over a retailer.

A Roman road whose alignment broadly corresponded with the extent of early Roman control in Britain; its possible use as an early frontier is debated.

The preserved remains or traces of an organism from millions of years ago, found in rock.

The preserved remains or traces of an organism from millions of years ago, found in rocks.

Coal, oil or natural gas formed from the remains of organisms over millions of years.

A carbon-containing fuel formed from the buried remains of ancient organisms over millions of years; coal, crude oil and natural gas are examples.

Coal, oil or natural gas, formed from the remains of ancient organisms over millions of years.

Coal, oil or natural gas: fuels formed over millions of years from the remains of living organisms.

Coal, oil or natural gas: an energy resource formed from ancient living material over millions of years.

A natural fuel, such as coal, oil or natural gas, formed over millions of years from the remains of living organisms.

Coal, oil and natural gas: carbon-rich fuels formed from ancient organic material over millions of years.

Coal, oil and natural gas formed from ancient organisms and used as energy resources; their combustion releases carbon dioxide.

All the fossils that have been found, together with information about their ages.

All the known fossils, which provide evidence about life in the past and how organisms have changed over time.

A settlement established or reorganised by a ruler to serve purposes such as military control, administration or trade.

A traditional story explaining the origins of a community, often linking its beginnings to heroes, gods and important institutions.

A traditional story explaining the beginnings of a city or community, often connecting its identity and institutions with heroes or gods.

Stories explaining the origins of a community and its institutions, often combining human actions with religious beliefs and moral lessons.

Four major Twelver Shi’a Hadith collections: al-Kafi, Man la yahduruh al-faqih, Tahdhib al-ahkam and al-Istibsar.

A coordinate identifying a map-grid square using two easting digits followed by two northing digits.

A design dividing a garden into four sections. The reconstructed garden at Pasargadae may be an early example.

The ancient theory that health depended on balancing four bodily fluids: blood, phlegm, yellow bile and black bile.

Death, judgement, heaven and hell: the four central realities considered in Christian teaching about the end of earthly life and eternal destiny.

A programme to improve agriculture, industry, defence, and science and technology, originally announced by Zhou Enlai in 1964 and pursued under Deng Xiaoping.

The Buddha’s four central teachings about suffering, its causes, its cessation and the path leading to its cessation.

Old ideas, old culture, old customs and old habits: the targets of a destructive campaign during the Cultural Revolution.

The mean of four consecutive observations in a time series.

The encounters with an old man, a sick person, a dead body and a holy man that prompted Siddhartha Gautama to seek a spiritual solution to suffering.