39 plural forms that might confuse writers

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