"Held water" is a phrase used to indicate that something is credible or true. Its antonyms, i.e., words opposite in meaning, would be those that signify unreliability, falsehood, or inaccuracy. A few such words are implausible, questionable, unreliable, untrue, lacking substance, and insubstantial. Their meaning directly opposes the concept that something "holds water" or stands up to scrutiny, indicating that it is weak and easily challenged. Using antonyms of "held water" could help in emphasizing the doubtful or dubious nature of a situation or claim, making it easier to convey the message accurately.