Forming regular plural nouns in English is a pretty simple concept, but that’s where the simplicity ends. English has so many different irregular plurals — and so many different types! There are plurals that are identical to their singular versions (sheep: sheep), plurals that change for count and noncount nouns (fish: fish, fishes), plurals that have held on to their Old English or Middle English endings (child: children), plurals that retain the endings from their source languages (criterion: criteria), a whole slew of words with multiple acceptable plurals (index: indexes, indices), and that barely scratches the surface of irregular nouns.
But there’s one subset of plurals that is rarely spoken of: homonyms (in the first sense mentioned here) that, for reasons of etymology, tradition, or convention, have nonhomonymous plurals — one regular, one irregular. For wordsmiths, these multiple plurals can be a punning opportunity, but for an automated spellchecker — and more importantly, for people trying to learn English as a second language — they can be a problem.
Here are just five of them to consider.
The argument over whether data is singular or plural has long been decided (it’s either, depending on context), but the singular datum itself deserves some scrutiny. As a word indicating a single piece of information that may be used for calculation or inference, the plural of datum is data.
But in surveying, a datum is a reference system that provides a known location from which to conduct surveys or create maps, and it takes a different plural. According to the NOAA, “There are two main datums in the United States. Horizontal datums measure positions (latitude and longitude) on the surface of the Earth, while vertical datums are used to measure land elevations and water depths.”
And to confuse matters more, surveyors can use datums to collect data about an area.
But die also refers to various manufacturing tools for creating specific shapes — as a mold, to cut screw threads, etc. Two or more of these tools use the regular plural dies.
Goose was likely one of your first grade-school stops when you started learning about irregular plurals. Geese almost always appear in flocks to honk, to hiss, and to litter public spaces with their waste.
But there are two other types of goose: The first is a smoothing iron with a gooseneck handle used by tailors. The second is, to quote Merriam-Webster, “a poke between the buttocks.” Either of these in the plural are gooses.
Media is so commonly used as a singular noun that people sometimes forget it was originally plural. Well it was, and often it still is.
As the material or substance used for expression or transmission — from paints to vinyl records to the telegraph — the plural of medium is media.
But a medium is also a person who communicates with the dead, and the plural for this type of medium is mediums.
Interestingly, both types of medium are derived from the same root: the Latin medius, “middle.” In both cases, the medium sits in the middle between two things. Just as the printed page sits between the writer and the reader to transmit the writer’s ideas, so the spiritual medium sits between the dead and the living to pass a message along.
When Dwight Eisenhower was made Supreme Commander of the Allied Expedition Force, tasked with planning the invasion of the European continent, his first logistical problem was that each of the participating forces — the U.S., Great Britain, and Canada (Russia was holding down the western front) — had its own staff of officers and enlisted men and women. General Eisenhower had to find a way to get these staffs to work together smoothly and efficiently.
The wizard Gandalf had a staff, too — not a group of people under his management, but a rod he used for general magicking and as a walking stick. There isn’t broad agreement on what he’d have if he’d carried two of them — staffs or staves. Garner’s Modern American Usage, Third Edition, states that “[i]n most senses, the plural is staffs,” but you can still find plenty of examples in closely edited text of staves to refer to these rods.
A third type of staff is the set of horizontal lines on which the notes of a piece of music are written. In musicology, the common plural of this type of staff is staves.
And in music, it can get more complicated. In piano music, the set of two staves — treble clef on the top and bass clef on the bottom — is referred to as a grand stave, or sometimes just a grand staff. (There are three staves in a grand stave for organ, the third one for the pedals.)
As people who deal with the intricacies of English every day, copyeditors sometimes don’t really notice how complex and counterintuitive our language can be for people trying to learn it. And this is only a handful of examples. What did I leave out? Log on and share your examples in the comments below.