In the English language, there are exceptions to every rule.

Some of the most maddening exceptions occur with spelling rules. For instance, it’s “i before e except after c”—unless it’s the fourth Thursday and there’s a full moon, right?

So, let’s look at “weird” plurals. And I say “weird” because pluralization is not always about adding an “s.”

With the singular form listed first, here are some words you can’t make plural just by adding an “s”:

• syllabus
• syllabi

• diagnosis
• diagnoses

• radius
• radii

• stratum
• strati

• nucleus
• nuclei

• focus
• foci

• fungus
• fungi

• crisis
• crises

• criterion
• criteria

• index
• indices

• appendix
• appendices

• ox
• oxen

• schema
• schemata

• seraph
• seraphim

• tableau
• tableaux

• die
• dice

Other words simply break the rules. For example, words ending in “o” are generally made plural by adding an “es,” such as potato/potatoes. But what about:

• memo
• memos

• cello
• cellos

Or how about:

• knife
• knives

• roof
• roofs

Or even:

• goose
• geese

• mongoose
• mongooses

And:

• man
• men

• woman
• women

• human
• humans

Then there are the words that are spelled the same in both the singular and plural form:

• deer
• moose
• sheep
• kudos
• premises
• shambles

And of course, there are words that are plural with no singular forms:

• alms
• amends
• doldrums
• pliers
• scissors
• shorts
• smithereens
• trousers

Readers, any other “weird plurals” to share?

Laura Hale Brockway is the author of the writing, editing, random thoughts blog, impertinentremarks.com.