Modern Slang #1: 'Fire' 🔥 Dialects: All (🇬🇧🇺🇸🇮🇪🇳🇿🇦🇺), predominantly US Meaning: Very good - typically of music (rap). In spoken, slang English, 'fire' can be used as a noun or an adjective to describe soemthing that is very good and popular. It is most commonly used to describe music, particularly rap music. 'Have you heard my new mixtape?' 'I have! It's fire.'