What’s Up with the Plurals of Alumnus and Alumna?
People often make the mistake of saying alumnuses when they want to use the plural of alumnus. Even more often, people make the mistake of saying alumnas when they want to use the plural of alumna.
But why is it that the plural of alumnus is actually alumni, and the plural of alumna is actually alumnae?
This all has to do with the fact that these are words that have been directly borrowed from the Latin language.
In the Latin language, you don’t make a word plural by simply adding an “s” like we do in English.
Instead, Latin uses a much more complicated “case system” to determine what the plural form of a word is.
A case system is a group of forms that a noun, adjective, or pronoun, can change into depending on how the word is used grammatically in a sentence. This means that a word in Latin will look different from when it is used as the subject of a sentence than when it is used as the object of a verb in a sentence.
For example, we can look at the simple sentence Canus lambit canum (the dog licks the dog). Canus is the Latin word for dog and lambit is how you say “he licks” in Latin.
If you notice, canus is used twice in the sentence, but spelled differently the second time. The first time it is spelled canus and the second time it is spelled canum.
They are both still the same word, but they have different spellings (different forms) because they are being used differently in the sentence.
Canus is in what is called the “nominative case” because it is the subject of the verb lambit. Canum is in the “accusative case” because it is the direct object of the verb lambit; that is to say, it is receiving the action of the verb.
This is the basic idea of the Latin case system. Latin actually has more than two cases (there are seven in total, with only 6 being used frequently), but that is not really relevant.
So what does this all have to do with the spelling of alumnus and alumna?
Well, when English borrows Latin words, it generally uses the nominative (subject) forms of the word. This means that when we want to make alumnus and alumna plural, we have to use the nominative forms that Latin uses.
But wait! Just because we have to use the nominative forms for both alumnus and alumna, that does not mean that they would look the same.
Not only does Latin have different endings depending on how a word is used, Latin also has different families of endings (called declensions), and different words will follow the rules of different families.
Alumna, which is the word used to describe women, is part of the family called the first declension. Alumnus, which is the word used to describe men, is part of the family called the second declension.
There are five declensions in total, and each has a different set of forms for every Latin case. This is why alumnus and alumna have different nominative plural forms from each other.
Now we can finally understand why the plural of alumnus and alumna in English are alumni and alumnae respectively. The second declension nominative plural form changes the ending of a word to -i, so alumnus becomes alumni, and the first declension nominative plural form changes the ending of a word to -ae, so alumna becomes alumnae.
While this explanation may have been a little complicated (as Latin tends to be), hopefully you can now understand why alumnus and alumna become alumni and alumnae in the plural.