A Roman walks into a bar and tells the bartender, “I’d like a martinus.” The bartender says, “You mean a martini.” “No,” says the Roman, “I only want one.”
English is a funny language — in both senses of the word. English incorporates words from other languages, and sometimes that means the usual rules don’t work. Usually, we add “s” to the end of a word to make it plural or “es” if the word ends in s, sh, ch, or z. But more than one stimulus are “stimuli,” not “stimuluses.”
How about those license plate frames that read “Alumni —University of [Wherever]”? Do they make you want to pull alongside and ask if the driver’s significant other also graduated from this alma mater? “Alumni” is plural. One male graduate is an alumnus. One female graduate is an alumna. Members of a group of female graduates are alumnae. Reference to a group of men and women or all men is the only time “alumni” is correct. Ah, Latin.
But what if it’s not Latin? The English plural of the Greek origin word “octopus” is “octopuses.”
And then there’s French. A French term may be necessary to the narrative or perhaps a French phrase is the best way to make your point. Something may be a fait accompli, but two or more of them are faits accomplis. More than one chargé d’affaires are chargés d’affaires.
The “s” to make a compound noun plural goes with the main word. The divorce client in front of you for the third go-round may have one father-in-law plus two ex-fathers-in-law. “Courts martial,” “notaries public” and “holes in one” are terms every lawyer should know.
English is full of exceptions to the rules. Plurals from Old English nouns include “women,” “children,” “feet” and “teeth.”
Spell-check will catch some plural mistakes. When in doubt, turn to the dictionary. In the absence of an authority, default to the standard addition of “s” or “es.” After all, we’re using English, not any other language.
A Roman walks into a bar and tells the bartender, “I’d like some beers.” The bartender says, “How many?” The Roman holds up two fingers: “Five.”