Cack/kæk/ Definition 1 of 3Pro Tip 1/3Very Informal Used in casual or humorous contexts, not in formal speech or writing. Watch where you step, there's dog cack! Pro Tip 2/3Mild Profanity Considered a mild swear word, so be cautious using it around strangers or authorities. I stepped in cack – it's everywhere! Pro Tip 3/3Archaic Usage It's an old word and not commonly used today, which may confuse some listeners. I found some rat cack in the attic; it's ancient!