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.