There are plenty of synonyms for the phrase "dead giveaway." It refers to something that is so obvious or easy to spot that it gives away a secret or intention. Some alternatives include "tell-tale sign," "giveaway clue," "obvious indicator," or "flagrant signal." Other words for "dead giveaway" include "deadly obviously," "indicative," "noticeable," and "evident." Context matters to determine the most appropriate phrase for the situation. For example, "tell-tale sign" or "obvious indicator" could work well when describing physical evidence, while "flagrant signal" might be better suited for describing a verbal cue. Regardless of the synonym used, a dead giveaway is a critical aspect of mystery novels, crime dramas, and other suspenseful stories.