Why isn’t it the “Ide” of March?

We don’t know where the word Ides comes from or why the Ancient Romans used plural words for singular dates. Thanks, Caesar. 

Today is the Ides of March, when Julius Caesar was notoriously assassinated in 44BC. Shakespeare immortalized the date when his soothsayer warned in The Tragedy of Julius Caesar: “Beware the ides of March” (1.2.19). Both of these are true: Caesar was killed on March 15 and a seer, according to ancient historians, did caution him the Roman ruler about the date, though didn’t exactly say Shakespeare’s famous words. But why is this day called the Ides and if it’s just one day, why don’t we call it an Ide?

ides full moon.jpg
The Ides originally marked the full moon each month. (Pixabay)

The tides of Ides

The Ancient Roman calendar had three major days: The Kalends marked the first of the month, the Nones the 5th or 7th depending on the month’s length, and the Ides the 13th or 15th. For March, as we know, the Ides fell on the 15th. Originally, this mid-month milestone would have corresponded to the full moon.

Kalends, from Kalendae, is rare instance of an archaic K in Latin. Kalendae appears to be related to the verb calare, “to call out.” On this day, after they observed the new moon, priests declared the number of days until the Nones and Ides. Just as we often pay our bills on the first of the month, so the Ancient Romans settled their accounts on the Kalends, hence calendarium, “an account book,” leading to our word calendar

Nones comes from Nonae, the plural of nonus, “ninth.”  The Nones fell eight days before the Ides, but the Romans counted their days inclusively, adding the target Ides to make nine. Our word noon is directly related to nonus: It comes from hora nona, the “ninth hour” of daylight. This was around 3pm for the Ancient Romans – and Anglo-Saxons, when the Church first borrowed the term, fully shifted to today’s 12pm either due to a customary midday meal or prayer time by the 14th century. The English nine also shares a deeper Indo-European root with nonus.

In some instances, the accusative case of these words were used when recording dates. For Kalendae, this was Kalendas, Nonae Nonas, which helps explain why English used Kalends and Nones.

As for Ides, it comes from the Latin Idus, rendered as Eidus. We simply don’t know where this word comes from. Eidus points to an Oscan form of Ides; a sister to Latin , the long-extinct Oscan was spoken southeast of Rome. The best guess scholars have is that Ides comes from some lost Etruscan word, perhaps meaning “to divide,” as the full moon so organized their months.

But why do we refer to a singular date – March 15 – as Ides and not Ide? At points in English, we sometimes did, but this technically breaks with history. The Ancient Romans always used plural forms for these dates. As Agnes Kirsopp Michels notes in The Calendar of the Roman Republic:

It is an interesting fact that in Latin and Greek the names of regularly recurring days are often plural, as are many of the annual religious observances which give names to calendar days.

Perhaps the fact of their recurrence lent a sense of plurality? Or perhaps plurality better accorded with the religious significance of these days?

But, Michels continues: “Why this should be true of some days and not of others is a puzzle.”

m ∫ r ∫


10 thoughts on “Why isn’t it the “Ide” of March?

  1. The post on Ides was very interesting. I don’t know that I’ve ever read, “we simply don’t know where this word came from” in any of your posts!

    Liked by 1 person

    1. Thanks! I suppose you’re right: I’ve featured quite a few words whose origins are disputed to the point that etymologists safely conclude their roots are unknown, but not as many ‘We just don’t know’. It’s the etymological equivalent of ‘Sorry, this bus is not in service’. It’s still fun to hop along, though.


  2. Thanks–I was wondering when these so-called “ides” were supposed to be and what they were (or “it was”), exactly.

    Funny thing, I’ve been watching “Cleopatra” a lot the past week–but just the first half because Marc Antony is a whiny drunk who annoys the hell out of me, but Rex Harrison’s wit as Julius Caesar’s cracks me up sometimes–very quotable. And that assassination scene–wow.

    Then I get to remembering that bit of Shakespeare’s Caesar (the film with Mason and Brando) and Caesar goes up to the soothsayer, saying like “well, it’s the ides of march” and the old man says something like “the day ain’t over yet.” That’s what I remember most.


    1. Thanks for reading! (Yeah, Antony was never my favorite, either, except in Shakespeare’s “Julius Caesar.” And I had forgotten Brando played Caesar! I still need to see that adaptation. From the 1950s, I think it was?)


  3. It has always been my understanding that March was Tax Time in and and went Rome. Civilizations always borrow from each other. For instance, Christmas was to provide a holiday, for the Believers, around the end of the year similarly to the ancient Pagan Holiday, even the trees and the wreaths. In early America, I had been taught that tax day was in March, perhaps as the nation grew vastly larger. In today’s Digital Age, they could probably move it up ti February[ but then, what would the procrastinators do?


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