The phrase "come to naught" means that something has failed to achieve any significant results or outcomes. There are various words and phrases that can be used as synonyms for this expression, which can help to convey the same meaning more effectively. Some suitable synonyms for "come to naught" include: fall through, go awry, be in vain, prove fruitless, fail, be unsuccessful, flounder, founder, fizzle out, collapse, peter out, and hit a snag. All of these synonyms suggest that something has not been successful or has not met with the desired results, which can be used interchangeably with the phrase "come to naught".