Latin, though dead through and through, has undoubtedly pushed its way into the English language in an important way. Not enough of us these days know how to wrangle it properly, though. “Quid est?”, or “What is that?”, will help you with Latin lingo and lore.
Is it octopuses or octopi (like your annoyingly insistent friend claims)? How do you say algae anyways? Are you really an alumni of that college? Why do we have these seemingly random exceptions to plural-forming conventions? Such are questions asked about Latin-derived plurals.
In English, we more-or-less use the same spelling for different forms and uses of nouns. For example, using the word “friend” as a subject, we would just write “friend”. If we used it as a possessive word, we might write “of the friend” or “the friend’s”. For the plural, we’d write “friends”. Using it as an indirect object might look like “to the friend” and as a direct object, it’d be “friend” again.
Latin is not like this–instead of surrounding a noun like “amicus” (Latin for friend) with little words like “of”, “to”, and “the”, or simply appending “-s” to words to create plurals, Latin declines nouns into several forms, each implying different usages. Just by appending different suffixes to the base of a word, I can indicate a subject or an indirect object, a direct address or a direct object, singular or plural, all by just changing the ending of the noun.
As you might have guessed, Latin also has forms to denote plural nouns. For example, the plural form of “amicus” (a male friend) is “amici”. The plural form of “amica” (a female friend), however, isn’t “amici” as well; it’s “amicae”. Because of even more complications with gender, there are multiple declensions, and depending on the noun, different plural ending forms.
Some Latin nouns have wormed their way into English today, and still retain some of their abnormal plural endings. Here’s your guide to identifying them and correctly using the plural form.
The first matter at hand is to identify when you have one of these Latin nouns. Most of these have one of three endings: “-a”, “-us”, or “-um”. For example, formula, fungus, and forum are all Latin-derived English nouns. No doubt it’s not always easy to identify these; there’s no particular rule, since we’re in English. The best way to be sure, though, is to check the context. Does it sound Latin? Could it have originated from Latin? Are you in a scientific setting? (Scientists love naming things in Latin.) For example, I know forum must be one of these Latin nouns, since in ancient Roman times, a forum was a large plaza, a meeting place; almost a “farmer’s market” for intelligent political (and the like) discussion.
Depending on the ending you have, the plural could be a couple of different forms.
- If the noun ends in -a, the plural form will end in -ae. (For the pronunciation savvy, -ae is said like the letter “I”.) However, of the three endings, this is the least frequent to make it into modern English. Err on the side of English on this one; a noun ending in -a is much more likely to be English than Latin-derived.
- In our example “formula”, the ‘correct’ Latin plural is “formulae”.
- Nouns ending in -a are usually feminine in gender (this doesn’t really have to do with the femininity of the object discussed, but nouns describing female people, non-concrete concepts and romantic ideas are often feminine).
- If the noun ends in -us, the plural form will end in -i. (-i is pronounced “ee”, like the letter “E”.) This pops up quite frequently in English language, actually.
- In our example “fungus”, the plural is “fungi”.
- -us nouns are usually masculine in gender.
- If the noun ends in -um, the plural form is debatable. Most of the time, it will be -a (just pronounced “ah”), but occasionally, you might see -i pop up.
- In our example “forum”, the plural is “fora”.
- -um nouns can be either masculine or neuter (neutral) in gender.
You can follow these rules to identify and correctly decline Latin-derived nouns yourself, but following is a list of particularly discussable nouns.
- radius: As you probably know from geometry class, the plural is indeed “radii” (with two i’s), and is said “ray-dee-ee”. This double i phenomenon is actually not uncommon in Latin, with nouns which have base stems ending in i.
- forum: As more virtual message boards pop up nowadays, the word “forum” is coming into more frequent usage. While a good portion of people choose to use the Latin plural “fora”, many more people say “forums”, and either way is fine.
- algae: If you look back to the plural rules, algae is actually a plural. However, “alga”, the singular, isn’t used often. The technical Latin pronunciation would be “ahl-guy” with a hard g, but it is conventionally pronounced (and thus accepted as a “correct” pronunciation) as “ahl-gee” with a soft g.
- alumni: Once again, this is a plural form. You could refer to a group of graduates as alumni, but only because when mixing males and females, we use the masculine form. A more accurate form of describing a group of female graduates would be “alumnae”. And what about you, yourself? No, you’re not an alumni of university. You’re an “alumnus” or an “alumna”, depending on your gender.
- antenna: The Latin plural for antenna is “antennae”, but it shares the spotlight with the equally-used “antennas”. Since both are used in everyday language, both are acceptable forms.
- media: Yeah, that’s a plural Latin noun! Nowadays, the word “media” is treated as a singular mass noun, but it is the plural of “medium”, referring to the different types of methods used to communicate information.
- octopus: Wait, that’s not a Latin noun. oktopous was originally a Greek noun, with a plural form of oktopodes. Although octopus deceptively contains the Latin-derived prefix for “eight”, and has that -us ending, it is not, in fact, a Latin noun. Thus, “octopi” as a plural for octopus is not technically correct as it were derived from Latin; “octopuses” would be more ‘right’. However, since language is shaped by what people choose to say, “octopuses”, “octopi”, and “octopodes” are accepted plurals in the Oxford English Dictionary. In the end, take your pick, but octopi is derived from a misconception.
These are just a sampling of all there is, but hopefully this list gets you started.
You may notice that these words frequently are able to take the Latin plural and the English-formed “-s” or “-es” ending. Neither is a wrong way to say it, but I personally like using the Latin forms when I can, because, Latin. It’s elegant. (As a side effect, it makes you sound smart. Just kidding.)
One does have to, in the end, realize that language can never be completely controlled by rules. Language is a method of communication, and whichever way humans choose to do it (and understand each other) is, after all, the “real” way. Even though, as a Latin student, I like saying “ahl-guy” and debating the correct plural of octopus, these nouns will never follow all the Latin rules; we’re in English! So take the “correct” way to do Latin with a grain of salt, and remember that if enough people decide to use a certain form of a word, it’s a “correct”, an acceptable form just because people use it.