Katharevousa, the “clean language”, was a more intellectual form of the Greek language that was suggested in the 18th century and got used in the 19th and 20th century in Greece and Cyprus. It was used by the state, the press and many authors but the common folk spoke the demotic, “the language of the folk”. Katharevousa was a more archaic in nature and compared to the demotic it sounded/sounds kinda pretentious. It was a bridge between the demotic and the ancient language, aiming to be a language with only Greek words in, without foreign influences. Katharevousa divided Greeks. It had passionate supporters and passionate haters calling each other names.

Its haters won eventually. Katharevousa stopped being used approximately 50 years ago. We are not taught Katharevousa in school. Children 50 years ago were taught Katharevousa only a little and children 60 years ago were taught Katharevousa for more years. Some phrases from Katharevousa have survived in modern Greek, like the phrase “by God” («μα τω Θεώ») using the now dead Dative. 

For some reason, the Greek Orthodox Church and its magazines still use Katharevousa - and sometimes they are made fun of for that because it sounds funny and pretentious to the rest of us who speak the demotic. Piests in Greece speak only the demotic, of course, but they write in Katharevousa when it comes to matters of the church. 

There was also a Greek series starting in 1998 called ‘Konstantinou kai Elenis’ (Κωνσταντίνου και Ελένης) where one of the protagonists was a conservative university professor and he used Katharevousa many times. Katharevousa there was used as a comedic device to show how out of touch the professor was, since by 1998 Katharevousa was a very old and outdated concept.