A cheerio is a small, crunchy biscuit that's often eaten with breakfast.
When people say "cheerio" as a goodbye, they're using the word in a different way. It's thought to have come from the phrase "good cheer," which means good mood or feeling. So, when someone says "cheerio" as they leave, they're wishing you a good day and hoping your mood stays happy. You might hear it in a more casual setting, like with friends or coworkers.
A small saveloy often consumed with tomato sauce at parties.
Goodbye, an interjection said upon parting.
