Other forms: snits
A snit is a really bad mood. If your brother is in a snit, you should wait a while to ask him if you can borrow his bike.
Snit is an informal word that's great for talking about an irritated or angry state. You might expect small children to occasionally fall into snits over sharing toys or having to take a nap. It's more surprising when you see a fully grown adult in a snit.