Do You Know the 35 Hardest Plurals in the English Language?

People is the plural of person. What rule does this follow?!

The plural of criterion is criteria. We think most people have more trouble with the singular form of this one.

The plural of human is humans. But if the plural of woman is "women," and the plural of man is "men," then why isn't the plural of human "humen"?

The plural of memo is memos. Hey wait ... aren't we supposed to add an "es" to words ending in "o"?

The plural of species is species. In some, very rare, instances, the word "specie" is used as the singular form.

The plural of ox is oxen. Does that mean that the plural of box is "boxen"? Sigh.

The plural of potato is potatoes. Similarly, the plural of tomato is tomatoes. But remember, never spell tomato "tomatoe." That's just wrong.

The plural of datum is data. We know what data is, but who knew that the singular form was "datum"?

The plural of elf is elves. Similarly, the plural of self is "selves."

Radii is the plural of radius. Well, that's not confusing at all.

Crises is the plural of crisis. For many words that end in "us," change the "us" to an "i" to make it plural.

The plural of roof is roofs. But if the plural of knife is knives, why isn't the plural of roof "rooves"? We're so confused!

Syllabi is the plural of syllabus. A syllabus is an outline, usually of a course.

The plural of Kennedy is Kennedys. The rule "change the y to an i and add es" does not apply to proper nouns.

The plural of scissors is scissors. Similarly, the plural of shorts is shorts.

The plural of hoax is hoaxes. Nope, that's not a hoax.

The plural of die is dice. This is another one where the singular form is more misunderstood than the plural form.

The plural of millennium is millennia. Add an "l" and you're talking about a generation: millennial.

The plural of phenomenon is phenomena. Similarly, the plural of automaton is "automata."

The plural of tableau is tableaux. Similarly, the plural of chateau is chateaux.

Diagnoses is the plural of diagnosis. Similarly, analyses is the plural of analysis.

The plural of cod is cod. Like deer and hair, cod is the same in both the singular and the plural forms.

The plural of moose is moose. Well, that's not confusing at all.

The plural of stylus is styli. Sometimes the word "styluses" is used for the plural.

The plural of hippopotamus is hippopotami. Similarly, the plural of rhinoceros is rhinoceri.

The plural of cul-de-sac is culs-de-sac. Similarly, the plural of brother-in-law is brothers-in-law.

The plural of passerby is passersby. We think that goes against the rules.

The plural of census is censuses. No, it's not censai.

The plural of axis is axes. Yup, the plural of axis is the same as the plural of axe.

The plural of cello is celli. But why isn't it "celloes"?

The plural of schema is schemata. A schema is a pattern or structure.

The plural of mongoose is mongooses. Wait, shouldn't it be mongeese?

The plural of aquarium is aquaria. We had to double check this one.

Indices is the plural of index. Huh? This is just one of those you have to memorize.