Brussels, Belgium—First-time students of the Greek debt crisis might fear they have stumbled on an alien language when they see some of the words European leaders use.

Here is a selection of the key neologisms and stock phrases that have made their way from social media into the "Grexit" vocabulary.

GREXIT: The withdrawal of Greece from the euro, the European single currency. A portmanteau word made by combining the words "Greece" and "exit". The term was reputedly first used in a paper by Citigroup economists Willem Buiter and Ebrahim Rahbari in February 2012. The alternative GREXODUS ("Greece" plus "exodus") has been suggested because the latter word is of Greek origin. Later spawned the word Brexit to refer to a potential British exit from the European Union in a referendum planned by Prime Minister David Cameron in 2017.

GREXIDENT (sometimes written GRACCIDENT): A chain reaction leading to Greece leaving the euro in a "chaotic, uncontrollable" fashion because of default or a bank run, despite efforts to keep it in. EU President Donald Tusk used the term on June 23 in a press conference, making it official after wide use on social media and in financial commentaries.

GREFERENDUM: A plebiscite called by Greece's leftist Prime Minister Alexis Tsipras for Sunday July 5 to decide on bailout reform terms offered by Greece's EU-IMF creditors, made by combining the words "Greece" and "referendum".

GAME OVER: Repeatedly used by Tusk, and also by Austrian Finance Minister Hans Jorg Schelling, to warn Greece and its creditors that time has run out.

THE BALL IS IN THE GREEK COURT/CAMP: A mantra for European leaders during the final days of Greece's bailout negotiations, meaning that it was up to Athens to respond to offers of a deal from its creditors. A German foreign ministry spokesman appeared to get the ball rolling on June 13, followed by ECB chief Mario Draghi who said the "ball lies squarely in the camp of the Greek government" and then taken up by many others. Tsipras later returned serve by saying that the ball was in the court of the European institutions.

WHERE THERE'S A WILL THERE'S A WAY: Used repeatedly by German Chancellor Angela Merkel to indicate there was hope of a deal but that political will was necessary, the term was then taken up by others including European Commissioner for Economic Affairs Pierre Moscovici.

JUNCKER FOOTBALL METAPHORS: European Commission chief is remarkably keen on football metaphors, saying on one occasion that the Greek bailout talks were a "game without extra time" and then on Monday mixing football with philosophy when he said he "would not want to see Plato play in the second division".