2 min read

This is a wug. Now you have two of them.

Three words that used to be plurals, and are changing in three different ways:

Candelabra used to be the plural of candelabrum, a multiple-armed candlestick holder. There are very few other English words ending in ‘brum’, and most of the words ending in ‘bra’ are singular (e.g. vertebra, penumbra, cobra, zebra, sabra, bra). Over time, candelabra has been used more and more often as the singular, perhaps most famously in the biographical movie “Behind the Candelabra” about Liberace; the corresponding plural is candelabras. This change presumably started as a simple error; some authorities would say it still is.

Agenda used to be the plural of agendum, from the Latin “which ought to be done”. People would write lists of things which ought to be done, and write “Agenda” at the top of the lists rather than “Things to do”, because they were pretentious and British.  Over time, agenda became the name of the list itself, rather than the items, and specifically the name of a list of things to be done at a meeting; the corresponding plural is agendas. There’s no error involved, just metonymy.

Data used to be the plural of datum, from the Latin “was given”. In statistics, you usually need a set of data, and the numbers are only really meaningful in context, not on their own. The new use has been to treat data as a mass noun, like information, something for which singular and plural are not relevant. There’s no error involved; there is a change of meaning.

Mass nouns take the same verb forms as singular nouns, so underinformed pedant wannabes sometimes claim data is being treated as singular. The simplest way to see that this claim is wrong is that data has no plural. No-one regards datas as correct English, although new singular count nouns very reliably form plurals with ‘s’.