Key terms & definitions

The division between the western Catholic and eastern Orthodox Churches, conventionally dated to 1054.

President Lyndon B. Johnson's programme of domestic reforms aimed at reducing poverty and inequality and improving access to education and healthcare.

The most intense phase of Stalin’s mass repression, usually dated to 1936–38.

A piece of armour protecting the lower leg, especially the shin.

Armour protecting the lower legs.

Armour worn over the lower legs to protect the shins.

An excessive desire to acquire or keep wealth or possessions, especially at the expense of other people.

A selfish desire to acquire more wealth, resources, territory or power.

An incendiary weapon used by the Byzantines, particularly against enemy ships.

Land around urban areas where development is restricted to preserve openness and prevent settlements spreading into one another.

An area of land around a settlement where development is restricted to help prevent urban sprawl.

An approach to designing products that aims to reduce environmental impact throughout their life cycle while meeting users’ needs.

Land that has not previously been developed, such as farmland.

Land that has not previously been developed, such as farmland or other open land.

The natural warming of the Earth's surface and lower atmosphere caused by greenhouse gases absorbing outgoing long-wave radiation and emitting some energy back towards the surface.

The natural process in which atmospheric greenhouse gases reduce the rate at which energy escapes to space, maintaining Earth at a temperature high enough to support life.

The warming caused when gases in the atmosphere absorb infrared radiation emitted by the Earth and re-emit it in different directions, including back towards the surface.

The natural warming of the Earth's surface and atmosphere because greenhouse gases absorb outgoing radiation and re-radiate some energy towards the surface.

A gas in the atmosphere that absorbs and emits outgoing long-wave radiation, such as carbon dioxide or methane.

A gas in the atmosphere that absorbs outgoing long-wavelength radiation and helps keep Earth warm.

A gas that absorbs infrared radiation emitted by Earth and transfers energy to the surroundings, warming the atmosphere.

A gas that reduces the rate at which thermal energy escapes from Earth to space; carbon dioxide is an example.

A gas that absorbs radiation emitted by the Earth and re-radiates energy, helping to warm the surface and atmosphere. Carbon dioxide and methane are examples.

A gas that contributes to warming by absorbing heat radiation that would otherwise escape from Earth into space. Carbon dioxide is an example.

A gas that traps heat in the atmosphere, such as carbon dioxide or methane.

Gases, including carbon dioxide, that absorb outgoing heat and contribute to warming the atmosphere.

A network of green spaces and natural features managed to benefit people and wildlife. Water features are often included through the term blue-green infrastructure.

A government document setting out ideas for discussion and consultation, which may lead to proposals for legislation.

An area of vegetation within a settlement, such as a park, garden or planted space around buildings.

Marketing an activity or business as environmentally friendly when its actual practices do not justify that claim.