breakneck Synonyms

extremely fast unchancy swifter swift subitaneous speedy snappy rushing runaway reckless rash rapid quick precipitous precipitate vertiginous whirlwind gone off half-cocked very fast supersonic sonic slap bang high-speed nippy hotheaded spiralling high-risk zippy alacritous daredevil winged precipitant nimble FAST express expeditious excessive dizzying dizzy darting dangerous careless brisk breathless blistering allegro accelerated fleet flying minacious