DESIDERATA
Go placidly amid the noise and the haste,
and remember what peace there may be in silence.
As far as possible without surrender
be on good terms with all persons.

Those are the opening lines of Desiderata, by Max Ehrmann, originally written in 1927. The text has a rather complicated history of publication, and for a while in the ’60s and ’70s was distributed in ornate little A4 posters, like the one above, but marked “Found in Old Saint Paul’s Church, Baltimore 1692”. So prevalent was this version on the walls of student flats when I was at university, I was later rather surprised to discover it was of more recent pedigree, with an actual named author.

It ushers in the long-delayed final post in my trio about Latin plurals. I’ve previously written about the plurals of words ending in -us and -a, so this time it’s the turn of -um. In Latin, these words are second declension neuter, and they take -a as their plural ending. And desiderata is the plural of desideratum, “desirable thing”.

Desideratum/desiderata is a pairing that still feels Latin, and there’s little tendency to regularize to “desideratums”. Several others fall into this category, among which are: corrigendum/corrigenda, ovum/ova, phylum/phyla, stratum/strata, spectrum/spectra, serum/sera, simulacrum/simulacra, erratum/errata, quantum/quanta.

Some, like curriculum/curricula, rostrum/rostra and crematorium/crematoria have a fairly fixed dominant relationship with a minority regularized plural ending in -s, as in this example from the Google Ngram corpus:

Some are in a protracted neck-and-neck tussle between the Latin and regularized plural, likes solarium/solaria and  gymnasium/gymnasia:

Some Latin plurals have fairly recently lost the battle against regularization. In the Google corpus forum/fora lost out to “forums” back around 1930. But it wasn’t until the 1980s that “stadiums” became the preferred option for stadium/stadia:

And some Latin plurals have just never been that popular, like mausoleum/mausolea, for which “mausoleums” has been the more popular choice for a couple of centuries:

Finally, there are words for which the Latin plural form is essentially never used: album/albums, asylum/asylums, lyceum/lyceums, museum/museums, premium/premiums. To that list we can add the Latin names of plants, which generally take regularized plurals: antirrhinum/antirrhinums, chrysanthemum/chrysanthemums, delphinium/delphiniums, laburnum/laburnums, nasturtium/nasturtiums.

A few Latin plurals in this group have taken on an independent life of their own. Agenda is the plural of Latin agendum “that which is to be done”, but is established as a singular noun in English. Media, plural of medium, is a label for the various modes of mass communication—newspaper, radio, television, electronic—and has been edging towards becoming a singular mass noun. That process has been going on for a century, with the singular usage slowly gaining parity with the plural, though the Oxford English Dictionary still classifies the singular form as “erron.”

Pretty much the same thing has happened to data, which has wandered off from just being the plural of datum, and become a concept in itself:

Candelabra is the plural of candelabrum, “candlestick”. But the construction of multiple candlesticks on a single base is so common that candelabra has quite reasonably mutated into a singular noun.

And I used to think that treating bacteria, the plural of bacterium, as a singular was a fairly recent innovation, but it’s been going on for decades:

There seems to be no good reason for it, apart from the fact that people hear the word bacterium less often, and may be unaware of the singular form.

There are a few -um words that are not Latin, and so do not take a Latin plural—conundrum and panjandrum are invented words, harmonium and vellum are French, begum is Urdu.

And then there are words which are Latin, but not second declension neuter nouns. These too take regular plurals. Factotum is an instruction: “do everything”. A Johannes factotum was a “John-do-everything”—a jack-of-all-trades. Nowadays it refers to employees who are entrusted with complete control of their employers’ affairs. Nostrum means “our”, as in the Roman name for the Mediterranean: Mare Nostrum, “Our Sea”. The word is applied to quack remedies and patent medicines because they are recommended by the person who prepares them (“our medicine”). Pendulum is a Latin adjective, meaning “hanging down”. The plural pendula can be defended as the corresponding plural adjective, but pendulums is much more common. Quorum means “of whom”, and its current usage derives from a standard Latin phrase calling together members of a committee: quorum vos [John Doe] unum esse volumus—“of whom we will that [John Doe] be one”. A variorum is a collected edition of an author’s work, together with notes on the text. The name comes from Latin editio cum notis variorum, “edition with various notes”.

Finally, a vade-mecum is a little book or manual suitable for carrying around with you. Of which, in my opinion, there can never be too many. Again, the name is an instruction: “go with me”. I’m fond of this word, and I remember exactly how I first encountered it. Like many medical students and paediatric residents, I carried around a copy of Ben Wood’s A Paediatric Vade-Mecum in the pocket of my white coat when I was training on the children’s wards. Mine was the green eighth edition, the envy of those stuck with the pink seventh edition.

It was a treasure-trove of handy facts, and I remember it fondly. So I was a little saddened to find that it seems to have expired with its fourteenth edition in 2002—this vade-mecum no longer goes with anyone. Replaced, no doubt, by a phone app.