The word “Ides,” as in “Ides of March,” denotes a single and singular day. But is the word itself singular or plural?
But why is “Ides” plural, and what does the word actually mean?
A (mercifully brief) lesson about the Roman calendar: each month had three nodal points—Kalends, Nones, and Ides—from which the days where reckoned backward. The Kalends fell on the first, the Ides on the thirteenth or fifteenth (depending on the month), and the Nones eight days before the Ides. All very confusing to us, though it must have seemed perfectly natural to the Romans, since their calendar had been handed down through countless generations.
Modern scholars speculate that Kalends, Nones, and Ides had something to do with the crescent, first-quarter, and full moon respectively. But what did the plural Latin word "Idus" mean?
Did I mention that the Roman calendar, and the words that went with it, had been handed down for countless generations? People tend to forget a lot over the centuries. By the time the Romans started reflecting on their long history and recounting the origins of this and that, including "Idus," the meaning of the word had been forgotten. Ancient scholars could only speculate.
A canvass of the ancient sources provides no solution as to where the Latin word "Idus" came from, or why it was plural.
Our oldest Roman source is Varro’s "On the Latin Language," dating from the first century B.C. Varro thought "Idus" might have come down from an even earlier civilization, the Etruscans, who, according to Varro, called that day of the month Itus. (It was a Roman commonplace to assign Etruscan origins to things too far back to recall; things Etruscan had the hazy glamour of antiquity.) But Varro gave no definition for either the Latin or the Etruscan word.
The query pops up again in Plutarch’s "Roman Questions," written in Greek in the first or second century A.D. Plutarch says the Romans “name the Ides as they do…because of the beauty and form [Greek eidos] of the full-orbed moon.” So the words “Ides” and “idol” would have a common origin—but the idea of Roman calendar names stemming from Greek origins seems quite unlikely.
Writing much later—in the fifth century A.D.—Macrobius in his "Staturnalia" repeated Varro’s speculation that the word was Etruscan in origin, and added that this Etruscan word meant something like “Jupiter’s guarantee,” since on the day of the full moon light was granted to mortals not only by day but also by night. Clearly unconvinced of this explanation himself, Macrobius listed a number of other etymologies, “all fanciful” according to his 20th-century Loeb translator.
So, a canvass of the ancient sources provides no solution as to where the Latin word "Idus" came from, or why it was plural. (I won’t discuss here why some of us choose to capitalize "Ides," "Nones," and "Kalends," and others do not, or the equally obscure origins and meanings of "Nones" and "Kalends.")
"Idus" was plural to the Romans, and “Ides” was plural to Shakespeare. Thus (and perhaps because an -s ending makes many words plural in English) to me it feels right to say, “The Ides of March approach.” “The Ides of March is a day to beware,” sounds sweet to my ear as well, perhaps because “Ides of March” constitutes a single thing, despite the plurality of one component. But to me it seems jarring and downright displeasing to say, “The Ides of March are my birthday,” since the verb equating “Ides” and “birthday” agrees with one but not with both.
My advice, as a professional novelist: Always be consistent within a given text, and simply avoid any awkward-sounding construction. And by all means do not beware the Ides of March. Celebrate the day instead—perhaps with a visit to your local bookstore.
Image of The Death of Julius Caesar © Vincenzo Camuccini