Understanding Brexit is difficult – and the terminology swirling around the United Kingdom’s bid to depart the European Union often makes things even harder.

In a bid to bust the jargon, here is a brief guide to the key terms of the Brexit saga, in alphabetical order:

Article 50

The exit clause within the Lisbon Treaty, the terms of which form the constitutional basis of the EU. A member state must invoke the treaty before it can formally and legally leave the bloc. The UK triggered Article 50 on March 29, 2017, becoming the first EU member to do so. The article allows a departing country two years to negotiate an exit deal, a period that has been extended by the EU for the UK.

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Backstop

A safety-net provision within the withdrawal agreement brokered between former British Prime Minister Theresa May and the EU which prevents a hard border being erected between Northern Ireland, a constituent part of the UK, and the Republic of Ireland, an EU member state, if a trade deal has not been agreed between the EU and the UK by the end of any transition period.

Under the terms of the agreement, the whole of the UK will remain in a customs union in relation to trade in goods with the EU “unless and until” the bloc agrees there is no prospect of a return to a hard border.

Brexit

The term for the UK’s move to renounce its membership of the European Union following a June 23, 2016 referendum. More than 33 million voters took part in the poll, with 51.8 percent opting in favour of leaving.

Former British Prime Minister Theresa May failed to get parliamentary approval for the withdrawal agreement her administration brokered with Brussels [File: Dylan Martinez/Reuters]

Canada model

Pursuing the so-called “Canada model” would mean the UK attempting to strike up a free-trade deal with the EU outside of the single-market model once it has left the bloc. Canada’s deal with the EU, known as the Comprehensive Economic and Trade Agreement (CETA), means it enjoys almost completely tariff-free trade in goods with the bloc. Under this model, the UK would not have to contribute to the EU budget and would not be bound by the single market’s laws, such as allowing for the free movement of people.

Customs Union

An agreement under which two or more countries agree not to impose taxes on imported goods from one another and to apply a common tariff on goods imported from countries not party to the agreement.

Under the terms of the EU’s customs union, goods that have been legally imported into the bloc can circulate throughout its member states with no further customs checks and member states are forbidden from negotiating trade agreements separately from the bloc.

Deal

This refers to the UK departing the EU with a brokered agreement on the terms of its withdrawal and future trading arrangements with the bloc.

European Union

A 28-member political and economic bloc. More than 500 million people live within EU member states, according to Eurostat, the EU’s statistical office.

Hard border

Because of Brexit, a physical border controlled and protected by customs authorities, police or military forces could be erected between Northern Ireland, a constituent part of the UK, and the Republic of Ireland, an EU member state.

This raises concerns about the future of the Good Friday Agreement, a peace deal signed in 1998 which helped to end the Troubles – a conflict in Northern Ireland between nationalists in favour of uniting Ireland and unionists in favour of the country remaining part of the UK.

The Good Friday deal removed security checkpoints along the border and helped make it all but invisible. It did not mention borders or customs.

Discussions over the Irish border have dominated EU-UK Brexit negotiations [File: Peter Morrison/AP]

Hard Brexit

There is no strict definition of hard Brexit, but it is generally accepted to mean a version of withdrawal from the EU which would see the UK leave the bloc’s single market and customs union. A hard Brexit would also likely see the UK stop paying into the EU’s budget and end freedom of movement, a founding principle of the union which permits citizens of EU member states to live and work in any part of the bloc.

No-deal

The UK leaving the EU with no brokered agreement on the terms of its withdrawal or future trading arrangements with the bloc.

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Such a scenario could lead to economic disruption, with businesses and individuals throughout the UK and EU potentially affected.

The Office for Budget Responsibility, the UK government’s independent forecasting body, warned in July that a no-deal departure from the EU would shrink the British economy by two percent and plunge it into a recession.

Norway-style compromise

Under the so-called “Norway-style compromise” approach, the UK would remain in the bloc’s single market, otherwise known as the internal market or the European Economic Area, after it has formally left the union. As such, Britain would be able to trade freely within the bloc while also striking trade deals with non-EU countries. It would also have to make financial contributions to the EU budget and accept a significant proportion of the bloc’s law, however, including the continued free movement of people, goods, services and money.

People’s vote

The name coined by pro-remain campaigners for a possible second referendum on the UK’s EU membership.

They argue that the Vote Leave movement misled the public about the benefits of quitting the bloc.

Brexit has repeatedly plunged British politics into crisis mode in recent months [File: Henry Nicholls/Reuters]

Single market

The EU’s single market covers all member states and four other countries – Iceland, Lichtenstein, Norway and Switzerland – and permits people, goods, services and money to move around freely as within a single country. Common rules and regulations are devised, implemented and adhered to by its members.

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Soft Brexit

There is no strict definition of soft Brexit, but it is generally accepted to mean a version of withdrawal from the EU which would see the UK remain part of the bloc’s single market and customs union, or both. A soft Brexit could also include UK concessions to aspects of the freedom of movement principle.

Transition period

The period during which negotiations on future trade arrangements between the UK and the EU will take place.

Any transition period is contingent on the UK leaving the bloc with a withdrawal agreement, without one, no such period would ensue.

Withdrawal agreement

May‘s brokered deal with the EU on the terms of the UK’s departure. The 585-page draft agreement includes provisions on citizens’ rights, the transition period and the so-called “backstop arrangement” concerning the Irish border, among other things.