Months in Greek: formal and everyday names, romanisation, IPA, dates

Formal -ιος and everyday -ης: two names for each month

The formal names are learned forms of the Roman months as Koine Greek wrote them: Ιανουάριος from Latin Iānuārius, Μάρτιος from Martius, Δεκέμβριος from Decembrius. They are the forms that CLDR gives to software set to Greek, and they decline like masculine nouns in -ος.

The everyday forms are the months as spoken Greek reshaped them over centuries. Wiktionary traces Γενάρης to Medieval Greek Γεννάριος, adding that it has nothing to do with γέννα, birth, despite the look; Φλεβάρης comes from a Medieval Greek Φλεβάρης, a reshaped Φεβρουάριος, so the two count as doublets. Οκτώβρης is inherited from Medieval Greek, while Σεπτέμβρης and Δεκέμβρης add a formal m to the old spoken Σεπτέβρης and Δεκέβρης. Wiktionary labels Απρίλης as colloquial or less formal.

Both sets are correct months in Greek, and the choice is one of register. In a written date the formal genitive is the form CLDR uses, while a sentence such as τον Σεπτέμβρη in the table below shows the everyday form at work.

Writing dates: the genitive and the national days

A Greek date puts the day first, then the month in the genitive, then the year: 28 Οκτωβρίου 2026, the twenty-eighth of October. That is CLDR's long pattern for Greek, and with a weekday in front the full form reads Τετάρτη 28 Οκτωβρίου 2026. In figures Greece writes day and month first with slashes, 28/10/26 in CLDR's short pattern.

Some dates are names in themselves. The twenty-eighth of October is Ohi Day, Επέτειος του Όχι, a national holiday in Greece and Cyprus that recalls the refusal of the Italian ultimatum on 28 October 1940.

To say in a month, Greek uses τον with the accusative, or the preposition σε fused with the article: τον Μάιο or στον Μάιο, in May. Both the formal and the everyday names work here: τον Σεπτέμβριο and τον Σεπτέμβρη both mean in September.

Capital letters, accents and the polytonic forms

Greek writes the months with a capital initial, as it does the days of the week. Wiktionary lists them as capitalised proper nouns, and CLDR prints every Greek month name with a capital in both the full and the short forms.

Modern Greek uses the monotonic system, introduced by law in 1982, with one accent mark, the tonos, and the diaeresis. Before that, Greek was written in the polytonic system with breathings and three accents, and older printed sources show the months in that form: Ἰανουάριος with a smooth breathing, Αὔγουστος with a breathing and an acute on the υ. The months in many languages table keeps the Greek row in these older polytonic spellings, together with Μάϊος, the Koine form with a diaeresis that Wiktionary records as the source of Μάιος.

In monotonic Μάιος the diaeresis is left out, because the accent on α already shows that α and ι are separate vowels. It returns in the genitive Μαΐου and the short form Μαΐ, where the accent moves away.

Common mistakes with the months in Greek

A typical error is the nominative in a date: 28 Οκτώβριος instead of 28 Οκτωβρίου. The genitive is required because the date means the twenty-eighth of October, and the accent shifts with it.

A second is mixing the two sets inside one phrase, such as a formal genitive with an everyday nominative in the same list. Writers usually pick one register and keep it. Third, the months in Greek take a capital initial, so a lower-case ιανουάριος, copied from French or Russian habits, is a spelling error. Finally, romanised forms differ: ELOT 743 gives Fevrouários for the modern word, while Wiktionary romanises the Koine source as Phebrouários, following ancient pronunciation.