If you want to send some writers into a panic, ask them to spell the plural of crisis. You’ll get a lot of strange answers, from crisises to crisese.
Alas, the plural of crisis is crises. All you have to do is change the last i to an e.
Usually when a noun ends in s, you have to add an es to get its plural form. When a noun with Greek root ends in is, however, those two letters are changed to es to get a plural form.
So, there’s no need to call out the National Guard. Just remember the simple is>es rule, and you’ll have it all under control.
My name is Rob Bignell. I’m an affordable, professional editor who runs Inventing Reality Editing Service, which meets the manuscript needs of writers both new and published. I also offer a variety of self-publishing services. During the past decade, I’ve helped more than 300 novelists and nonfiction authors obtain their publishing dreams at reasonable prices. I’m also the author of the 7 Minutes a Day… writing guidebooks, four nonfiction hiking guidebook series, and the literary novel Windmill. Several of my short stories in the literary and science fiction genres also have been published.